I don't track purchases at all, I track savings. I find that much more sustainable. I have a savings rate goal (50%), and automatic withdrawals to make that goal. If I can't pay my bills without dipping into the savings then I'll have to reevaluate my spending only then. As long as my savings rate is what it needs to be I don't worry about spending money.

This sounds like a good way to do it.

I'm a freelancer with variable income so I can't do a fixed investment rate. For me it's useful to see what was the actual rate vs. what I'd like it to be, and the high level view is quite enough to track that.