I have limited resources, and so I discard or apply filmmaking rules and techniques based on my particular situation. That's my approach in the simplest form. I learn what I think I have to know, and disregard things other people are telling me if I think it doesn't help my situation.
I believe I understand your position/situation, or at least understand it well enough to make some judgements about it.
I'm not disputing at all that your approach is the best for you in your current situation. I'm not saying there's anything at all wrong with filmmaking being a hobby but I'm presuming, maybe incorrectly, that at some stage you wish to move beyond no budget amateur filmmaking? If not then your best route is most likely to just keep refining/developing your current approach. If you do want to move on, then at some stage you're going to have to completely change your approach. If this is the case, then much/most of the knowledge, skills and experience you've gained so far will have been wasted, you will lack much of what you will need and worst still, you may not even realise until it's too late what what skills/knowledge you need. In fact, it's possible that your experience to date will make it more difficult to transition to the new approach than a novice filmmaker who doesn't yet have an old approach to overcome. Let me explain using your example:
I completely understand why you feel this way. It's actually the correct way to feel in any professional environment. For instance if I told you "Can you make this scream sound like an echo in a cave?" and you said "Yes." I would have no reason to doubt you.
Ahh, the rabbit hole goes much deeper than that! My response below goes to the heart of the original poster's question (and my response to it), as although we're now talking about sound design, the basic principles/approach are just as applicable to cinematography or indeed to any other creative film craft.
No, I probably wouldn't say "Yes" in the first place! Assuming that the scream in question was not actually occurring in a scene set in a cave and you just wanted that cave echo effect to signify a flashback, premonition or some other "inside the character's head" POV scenario, my response would be along the lines of; "what are you trying to achieve, what is the background to character's emotional state and motivation, how do you want the audience to respond/feel?". The answers to all my questions would not exist in the script (or would be ambiguous) because I obviously wouldn't need to ask questions which my reading of the script had already answered. Based on your answers, my understanding of the story/script, the footage/edit and whatever else might be going on (music for example), I would present you with a couple of options which are more inventive and effective than the old cliche'd big chamber/cave echo effect. All this raises a few points:
1. By telling me what effect you want (a cave echo), you are not employing me to design the sound, you are effectively employing me to just to come up with a good implementation of a sound design you have already designed (decided upon). You would be wasting my creativity/experience/skills and the money you are spending to hire them! I would expect any student/rookie to be able to just dial in a cave echo effect in 30 secs or so, to do it particularly well would need a good Re-recording Mixer but in your example you are in effect the sound designer. Again, at the no budget/amateur level you acting as sound designer (as well as director, etc.) maybe the best solution but at the budgeted/commercial level, where you need a professional sound designer, I can't think of anything less efficient than hiring a pro sound designer and then the design of the sound actually being done by a part-time amateur (you, the director)!
2. As the director, you need to have a far deeper knowledge, understanding and vision of the story than just what's in the script, otherwise you won't be able to provide answers (or will provide poorly considered answers) to my questions. Most amateur filmmakers are forced by their circumstances into considering what will work but at the commercial/professional level you have to think in terms of what will work best! What will work best for say sound design is not a director who creates a vision for the sound design themselves but a director with a story vision which provides sound design opportunities and facilitates the sound designer in doing the best job possible.
3. In TV dramas and micro budget films sound design tends to be a reactive art. By this I mean that during post production the Sound Editor is presented with a script, a final picture edit and the production sound and then designs and edits sound in reaction to these effectively unalterable materials. Provided the director and video editor have a decent understanding of how to use sound as part of their story telling, reasonably good results can be achieved. The top directors all use a Sound Designer rather than just a sound editor/s, a Sound Designer is collaborative role rather than a reactive one! With nothing but an editable script, the director and other HODs, the Sound Designer is able to collaborate and help the director develop a vision during development/pre-production with a more precise and detailed plan of the use of sound (together with the other crafts) to tell the story. The options presented by the Sound Designer may include a range of areas not possible when sound design is purely reactive, such as changes or additions to: the script, the story itself and any component of scenes, shots or locations which impact sound design or which sound design could impact. This approach is more effective than the director just providing sound design "opportunities", although both approaches require skill and vision on the part of the director.
The point I'm trying to make with all of this is that as far as your future is concerned you are thinking about the issues you will face in terms of the issues you currently face. Your problem at the moment is getting someone who can create the sonic effects you're after, or learning to do it yourself. You look at the professional/budgeted filmmaking world and imagine that this issue will disappear .. and you're right, in a sense it will, as I'd expect an intern/apprentice to be able to easily accomplish what you're after. However, in reality it won't, because "what you're after" will have to change, how you arrive at "what you're after" and then how it's implemented will all have to change and these changes require a whole lot deeper and more specific "directing" knowledge/skills/talents than your current situation allows you to develop or even potentially allows you to realise exists! Likewise, the advice you are giving is all based on your current issues, which may well be the exact same issues as many other no budget filmmakers have to face and may therefore be very good advice for a novice no budget filmmaker but, does the OP ultimately want to be a no budget filmmaker? If not, then IMHO, your advice is maybe not so good.
G
