There are other reasons to filter water besides removing giardia. Like crypto-sporidium, a nasty cyst. And dysentary. I once got giardia by drinking water from a fast-moving stream. Unbeknowst to me there was a croud of low-lifes 3 miles upstream. And recalling a incident from my hippie past, I once came upon a commune way way up in the mountains above Big Sur. Very remote with a pure pristine stream. Except when a deer dies and falls into the stream and you don't know it. Everyone there had dysentary.
i know this and in my day-to-day life i try to maintain healthy, regular bathroom habits. however this doesnt need to mean that i look forward to doing some business out in the woods three times a day........ i dont do much backpacking these days, but i dont think theres any serious concern about it not being healthy to reduce the number of daily BMs for a period of three or four days on a short trip