Like I have said before - most leaks are about your thought process - what's in your head. And this is kind of a tough one to break - from my personal experience. I too was cashing about 30% - but a lot of 4th and 5th (6th, 7th, bubbles too) place finishes made the graph a slow and plodding climb.
It's very tough to give this up because the graph is indeed climbing. And there is a great deal of personal pride to have a long string of final tables.
So you have got to be willing to change that graph from a nice, fairly smooth incline to Mr.Toads Wild Ride! Go from cashing over 30% to only cashing like 15% (with higher finishes like 1st and 2nd).
Let's like at a sample (fictional) of 100 tournaments.
$5.50 45 man on Carbon Poker
30% cashes - one third 4th place, one third 5th place and one third 6th place.
Entries = $550
Cashes = $618.70
Profit = $68.70
Now the same 100 tournaments at
15% cashes- one third 1st, one third 2nd and one third 3rd
Entries = $550
Cashes = $776.30
Profit = $226.30 (over 3 times as much)
These figures are totally fictional and have more to do with accommodating my limited math skills than anything, but hopefully it paints a picture that your brain can wrestle with in order to provoke replacing some success with greater success.
Like I said it can be a wild ride. I had a stretch of 17 tourney's without a cash. Very discouraging. But then 3 out of 5 cashes hit and evened all that out. Yup - variance is a bitch.