In reply to Ggilbs:
It is weird as people have said. There's few things to think about.
Pre-kids I used to sort climb a fair amount and I remember when I was climbing 7b-ish I still struggled on 6cs. When I was climbing 7c-ish I still struggled on 7as. I always thought it was psychological; something to do with thinking I ought to be able to get up something but struggling.
I've never had this with bouldering. My wife and I pretty much just boulder now. We have two kids so time is short and I can't imagine routing with two little ones running riot at the crag.
Anyway, bouldering-wise, I project around 7C to 8A. Below this I am usually pretty confident I can send something in a session. At project level I never assume I will be able to send things easily; I have climbed 8A in a session, I can (and I am currently continuing to) spend several seasons on the same project. Likewise, this summer I went to a new area and took two sessions to end a short powerful 7B.
I never assume I can do something, always approach things with an open mind and above all I attempt to flash every problem I try regardless. Sometimes you get lucky. Mostly you don't. Yesterday I almost flashed a 7B then took seven or eight more attempts to send it. I really enjoyed the process and learned a lot on it.