I practice using 1" aim point stickers at 15 yards, and a 1+3/4" steel hanger at 25 yards...got pretty consistent with them.
The longest squirrel rifle shot I ever had presented was about 25 yards, .45cal with 40grns Goex 3F, tried a head shot and apparently only grazed / stunned him...as I was walking over to pick up up, he 'woke up' and hauled butt. Have taken some closer like 10-15 yards with the .45.
I took two squirrels off the same tree one afternoon, 30 yards, .28ga & #5 shot.