For what it's worth...
I've got two 13-gallon plastic trash bins for water-changing purposes.
One I use for new water (via a 5 ft. hose attached to kitchen sink), the other for old/dirty tankwater. Gives me at minimum 10 gal. per water-change, which equates to roughly 20% on my 55 gal. tank. Takes me about 10 minutes.
I do this once a week. Once my fish are bigger, I can easily bump this up to twice a week. For that matter, I can easily step it up to a 40% water-change by simply filling both trash bins to begin with, and then draining old/dirty tankwater into my two 5-gallon buckets (several trips to dump out the 5 gal. buckets in the toilet = no big deal).
BV