tourney blind progression

[sketchy1]

i posted this on RGP and no one helped so i figured this was as good a place as any to seek help.

I'm working on a blind progression right now for my tournament... we
have around 20-30 people, $30 buy-in NLHE tournament. We're gunna do 6-7
person tables, with $30 in chips per person. Here's what I have right now,
planning on increasing them every 25 minutes with a 10 minute break every
hour. So basically, every 2 levels of progression would be an hour in
length.

Level Ante Small Big
Start 0 0 1.5
1 0 1 2
2 0 1.5 2.5
3 0 1.5 3
4 0 2 3.5
5 0 2 4
6 0 2.5 4.5
7 0 2.5 5
8 0 3 5.5
9 1 3 6
10 1.5 3.5 7
11 2 4 8


As of now, I think this should be OK, but I've never planned a
progressive blind system for a tournament so I thought I'd see what everyone
thought. After that point I might just start doubling blinds/ante if it
keeps going on as people are eliminated or like every 25 minutes. After 5
hours or so I think we should be to a final table, so doubling should be ok
by then. Does this look fine or is it too light on progression or any other
thoughts? I was thinking also instead of just doing a system timed, maybe
increasing them as people are eliminated per table. So when a table of 7 is
trimmed to 6, maybe doubling the blind, and after it's to 5, adding an ante
and doubling the blinds again, and from there on.

Any information would be appreciated.