What is the safest amount of money to have in reserve during a season?

See, I've played F1M24 a lot by now. I've started to pick up the most optimal strats, and development is a breeze. But JUUUUST to be safe with things like random events, parts manufacturing, designing, ey cetera, I try my best to have at least 6 million at all times so I don't go in the red.

6 million is a good one for me because it gives you some breathing room if you have a particularly costly week, like several parts worn out, random failures, and all that, while also giving you space to regain all that lost cash by getting the race targets.

Do any of you try to keep your balance to an exact number, or do you just go fuck it and do whatever you want?