Hi,
I think it would be great if the current robbery system woud change a little bit. Right now The Crime City is the most difficult robbery that even with Police reinforecemtns event requires around 600k power that could be easly achieved around day 20-25. That means that building your stats after that became irrelevant for the robberies. You have no bonus for having stats higher that 600k.
I thought about connecting the level of your character with robberies power. For example from lvl 1 to 8 you have an acces only to Normal difficuly level and standard power requiremens for robberies. From levels 9 to 12 you have a Hard difficulty level that doubles the power required to do the score and also doubles the reward and on 13th level you have a Expert difficulty level where both required power and rewards are tripled so for example The Crime City would need around 1.4M robbery power to do the score.

This could be adjusted however it is just an idea.