Trigger,
Once you have one and see how simple they are to rinse out you will see that doing it every few days is no big deal at all. (maybe 30 seconds to clean out) In summer I do it about every other day just because to keep them super fresh. But in winter when the water is less likely to drain away clean due to the snow and ice I only do it every few days.
Cleaning is as simple as using your fingers or a small sponge like pad. Just a simple wipe around and pull the plug and let it drain. When you pull the plug the water level drops and new water comes in. I use that water to just rinse a little more and put the plug back in and let it fill till it shuts off.
I wipe and rinse the tub inside and the blue liner both.
They are good at keeping bird crap out as well. But in the summer if it is dry out birds might try drinking from them. Once in a while a bird might drown in the water. Each day when I feed and pet my deer I just peek in to be sure there are no birds floating. Over the past few years I have found maybe 4 or 5 birds like that in summer.