This is a _very_ open ended question with many angles. As I browsed my available options for drinking tonight, it made me wonder what other's logic, reasons and decisions are to decide which, and how many, different bottles to have open and ready to consume.
I've tried to maintain a few basic rules:
1. Variety without duplication - I like having options, but I avoid opening more than one bottle of a particular style or a profile I find very similar.
2. No more than two barrel proof bottles - It may take a while to empty these (1+ year) and I don't want bourbon to get too much air before I finish them. I recognize this may not be entirely valid for some or all bourbons, but it makes sense in my head.
3. Don't pay twice - If a bottle is not being consumed for whatever reason, find a creative way to make the bottle disappear through consumption or gifting to make room for something else I may enjoy better.
With these rules, I currently have 14 open bottles. I suspect it would take me about 10-12 months to consume the currently open bottles and I share about 20-25% with friends, so this stock will cycle through in approximately 8 months.