I agree the spray doesn't do as good of a job but either way its better than sanding.
I've recently come up against some old paint that's been applied over the original paint on bikes that aircraft stripper won't touch.
Gel definitely works better than the spray. It also helps if you put a big piece of heavy plastic over the project after applying stripper. It seems to work better than being exposed to all the air when working outside. Also, the hotter the temp is outside, the better it works.