I do the same, I wash the feeders every time I refill them. In cooler weather, that's at least every 3-4 days. When it's hot, it's no more than every 2 days before cleaning and refilling with fresh sugar water. So at that frequency, boiling the water doesn't make a difference at all.
In Illinois I certainly don't get the amount of hummers that you probably get in Texas, plus I have a ton of annuals and perennials planted just for the hummers, so they don't use the feeders all that often. I think they do it more when they feel like resting while dining since there's a ring around the feeder for them to perch.
