I do a quick check daily- we have a galvanized font and a small chick waterer (small plastic jug that flips over). I look to see how much water is in it, does it looks grimey? I dump it out when it looks dirty, and wash the outside of the trough and the inside so it doesn't feel slippery. That's it. Obviously, when we had a heat spell last week, I checked 3 or 4 times a day, and added ice to keep the water cool.
I grew up on a horse farm, and we did the same for the horses. Dump, swish, refill, scrub when needed. We never bleached, and it's not something I will do myself. I do think some are doing more than necesary, these are animals after all. But, to each his own! Having a routine insures that things get done. I also find that puttering around is relaxing, and if tht includes scrubbing, so be it!