I'm not a big fan of weekly weighing. Weekly measurements are too infrequent to even out "noise", whether from water retention, TOM, a big meal the night before, or just a blinky scale. It's too easy to get frustrated by a one-time bump up, or to get complacent from an unusually low reading. Daily measurements also fluctuate, of course, but somehow it's easier to ignore one outlier measurement when you know you'll get another number tomorrow.
If you're a data geek, you could measure daily, but calculate a three-day or five-day moving average of your weight. (Easy to do in a simple spreadsheet program like Excel.) This will even out noise and give a good sense of trends.
Or, you could throw out the scale altogether, and just go by how your pants fit, how you feel, whether your lifts are going up or down (you are strength training, right? :wink

, etc.
be strong//
K