I might have misunderstood the initial question, I took it to mean that he was using a single powerhead to run the ugf with no other functioning lift tubes. IMO this is barely adequate in a 20G but not in a larger tank, the ugfs I have used only had a single lift tube on each end until You reached 35g or larger. I would generally use 2 or more smaller filters for a larger tank because I liked areas with no ugf for my plants. As for cleaning the gravel regularly I do just the surface layers generally though I do stir the gravel sometimes, I also do only a third or so of the tank floor at a time.
I like using both a hangon or two as well as the ugf, they act as mechanical filters to remove gross debris. I replace the charcoal section with biomedia such as small lava rock fragments and that part seldom gets cleaned (just sometimes rinsed. The sponge pad gets washed fairly often. That way the filter keeps a good flow without wiping out the bacterial colony. Between the two filter types tank parameters stay very stable and since the power sources to the filters come from different circuits it gives me a little time cushion to fix things in case of a failure.