How much effort should I put in the essay?

I know I should always do my best, but I simply don’t have enough time to write my common app essay and all the other supplements accompanying each college I’m applying to (if you’ve seen my UMich post, you’d understand how hard I need to work on those essays). Which is why I’m asking if I can just put in enough to show interest, but not necessarily slave over it?
30 ACT
3.91 UW GPA
MI resident.

Thanks!