we only do bath about 3 times a week. my daughter loves it and is way hyper afterward, so we try and not do it around bedtime. kinda whenever it fits in. also, ds wants to get in there with her, and it turns into this big splashfest with the curtain closed - i don't have the nerves for that more often. we also do showers if we don't have much time.
as a side note, when we grew up we had to heat the water with coal (on the 4th floor!), so we had a bath once a week. i never knew it any other way, i guess, and we certainly weren't dirty kids.... that's what sinks are for, right? so if that's what you do sometimes, there's no problem with that.