How much of your monthly AI spend is genuinely unavoidable vs just you not managing context well?

Looked at my Anthropic bill this month and it was almost 3x what I expected. Went digging and most of the overage was from long sessions where I kept feeding the same large files back into context because I forgot to trim the conversation, plus a few runs where an agent got stuck re-reading the same directory before I noticed. None of that was the model doing useful work, it was just me being sloppy with session hygiene.

For people running this stuff daily, what's your actual ratio of necessary spend to spend you could have avoided with better habits? Has anyone found a workflow? such as starting fresh sessions more aggressively, summarizing before continuing, caching, that meaningfully cut this down without losing useful context?