What rule of thumb do you use for number validation when you’re pulling form 2-3 different sources?

My numbers never line up cleanly thanks to different defintions/update cycles/reporting periods so there’s always a mismatch that needs explaining, even if it looks comparable on the surface. This step along is eating a huge chunk of time, way more than the analysis in some cases, and it’s adding to the pressure when i need to get something out quickly

For those who try to reconcile differences across your datasets, do you do that manually or have some repeatable process? And how far do you go before you hit “close enough”?