Mine started out at 30,456 and has yet to move from there. (its only been a couple days since I got this installed)
Well nobody knows for sure exactly how weight is calculated, but the number of exposures has to be a key element, so unless your exposures, or web site traffic is constantly changing, or going up dramatically, I wouldn't expect much change in weight.
Traffic is increasing day by day, quess i need to be patient... and i aint complaining... im moving up slowly step by step gaining some positions..
Shawn already wrote that impressions have nothing to do with it... I've noticed, Google was dropping some old pages of mine from the index, so my weight went down. Now Google has index more pages, so my weight is going up again... I'm now waiting for the next PR update so I can see how much my weight will increase...