It's not the worst way of looking at things, but it sounds like it could be potentially problematic.

Like you mentioned, sometimes you just have to concede and buy stuff. It's life. Having to pause and have internal struggles about dependencies for every purchase that you make sounds exhausting. It sounds more like a burden than anything.

The only situation in which I would actively recommend this kind of thinking is when you're budgeting. It's perfect for that. Honestly, if you're keeping a budget (and doing it well), then I don't think you have to "view everything in terms of monthly costs". You shouldn't feel like you have to. Or, at least, that's how I feel about it, but to each their own I suppose.