If you've been painting for a bit and know you're going to be painting again in a day or two, you don't have to clean your brushes every day. Give them a dip in oil - I use walnut - and don't wipe them dry. Leave them in a tray like this paint roller tray from Home Depot I've got here, with the bristles angled down just enough that the oil won't run down and collect in the ferrule. That'll keep them wet for awhile, at *least* a day or two, without needing to be scrubbed every time! If you need to buy yourself even more time, a few drops of clove oil mixed in with your dip will keep them wet a *very* long time, but wipe them out extra well before you paint again!