I often have described karma as a balance in an account as you started to here. Yes, unlike western corruption of the concept, it is not about what goes around comes around. It is all about intent, and as you allude, there are deposits and withdrawals, which get balanced out but most likely in subsequent life cycles. The best article I have read on karma is https://medium.com/illumination/the-real-meaning-of-the-law-of-karma-will-blow-your-mind-f07fe413ebce