I seem to be the only person here who doesn't get sodium-related water retention, despite having varying amounts of salt, and sometimes quite a bit of it for medical reasons. Painkillers, on the other hand, can make me retain a good pound or so without anything else happening.
I find daily weighing far less stressful than weekly weighing would be. It's just a matter of routine, you know the individual numbers don't mean much, it's not something you build up to all week.

Good luck!