There is a distinct difference between road and off road hill climbing. I never walk on road. I have low gearing and so far have not have any issue getting up even the steepest of hills. I've had to stop and catch my breath a couple of times but can alway get started again and do. In fact, I have this mentality - I will not walk my bike - while on road!

Off road; tough, steep, rutty, rocky, gnarly terrain is different. If in super low granny, it's tough to get the traction to start climbing again which is why I'll walk. Again, pushing a heavy mountain bike up steep terrain is still alot of work. Once the trail levels out, I'll try my climb again.