I think that people do like a sense of progression. And there are scaling problems with progression. So I take the lessons of the EPIC6 Concept (See Also) to heart when I am doing a campaign that leveling up from a weak civilian is part of player expectation and fun.
What has worked best for me has been to scale about 6-8 levels of power over my usual 6-8 sessions of a campaign (I get bored easy and like to hop around to new genres a lot, lol) and base the reaching of those levels on cumulative in game rolls of natural 1 or 20. (Each nat 1/20 = 1 XP) I always reserve the right to give a level bump at one or two Key Milestones as well. (Example: The party just handled a major problem and are rolling into an even bigger one for the big Act 3 Climax. Everybody give yourself XP to get to the next level and figure out what Path or Class Loot you’re grabbing before next session.)
ETA: For Supers and some of the other genres where progression isn’t as entrenched in expectations, I just let them build powerful characters from the start, and we have fun till we’re done.