For me it depends - if I am just keeping tabs on the used market then I read the new today once a day. IF I am actively looking for a particular toy, I likely check that section 3-4 times per day - case in point - when I was looking for a cheap tube pre with 2 sets of pre outs, and enclosed tubes, I was on that Tube Preamp link many times per day. Now that I have sent the payment off for one, I am just checking once per day, waiting for the buyers remorse thang to hit, when I see a different pre that meets my needs for less show up... it will happen, but hopefully I will like what I bought enough, that it will just revert to following the market.
On that note, I am not sure why I follow the market for used high end gear at all - I guess it is just what I do, for the things that I am into. When I was building up Suzuki motorcycles, I was checking about 5 sites daily, following that market. Now that I have sold those all off, and come back to the audio game, I do the same for this.
Just my addictive personality back at it again I guess!
