The problem with your question is "normal" means many different things to different people. It also depends on the terrain people are doing. Long sustained climbs? You can always muscle through really short steep grades.

if you were asking me... with a 50-34 and a 32T on rear. I would prob only use that on 16%+ grades.
For sustained climbs (1 mile +)
34 x 25t on a 6-9% grade.
34 x 28t on a 9-15%ish grade.
once I hit 17-20% grades... I'm probably getting out of my saddle with a 28t. I can't sustain spinning at those grades for long.

I do a lot hill climbs in the area where I climb about 2000+ ft over 4-5 miles. Most of the sections will have 2 miles of 10% average grade.