I wanted to check if I have the correct numbers in my tourney set.
25 x 160
100 x 160
500 x 80
1000 x 160
5000 x 40
Total = 600
Will only ever be used in a single table with a T10000 or T20000.
That 600 chip set (160/160/80/160/40) will support up to 20 players with up to 20K stacks (8/8/4/7/2). It will also support 10 players with up to 35K stacks (16/16/8/14/3) or 25K stacks with re-buys. Plenty of T1000 and T5000 chips for color-ups in all cases.
Imo, 400 chips is the minimum needed for a decent single table T20K set with sufficient chips for color-ups and re-buys.
10 x 20K starting stacks (12/12/5/6/2):
120 x T25
120 xT100
50 x T500
75 x T1000 (includes 15x for T25/T100 color-ups)
35 x T5000 (includes 5x for T500 color-ups and 10x for re-buys)
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400 total chips. If bumping it up to 600 chips (with no two-table plans, ever), I'd go with 120/120/60//200/100. If you want to retain two-table capability, keep your 600 counts as-is (160/160/80/160/40).
A few other random thoughts and comments:
Typical re-buy rate for a well-structured event is 25-30% of the starting field size (two or three in a 10-player event). If your re-buy rate is higher, it's likely due to either: the buy-in/re-buy cost is too low for the bankrolls involved, the starting stacks are too small in relation to the starting blind levels, the blind levels are overly-aggressive, the re-buy period is too long, or some combination of those factors.
A starting stack of 8/8/4/2/1 is pretty awful. You don't need T5000 chips in a starting stack (especially one as small as 10K), and just two T1000 chips is woefully lacking. 8/8/4/7 works much better, 12/12/5/6 is preferred and works great, eliminating the need for unnecessary change-making which slows down the tournament.
Provided the starting stacks are properly constructed, there is no valid reason to subsequently add more lower denomination chips into play that will just need to be removed again later in the event. That means that color-up and removal of T25 and T100 chips are best handled by T1000 chips (a workhorse chip later on, so more are needed later), and T5000 chips are used for re-buys and for the color-up and removal of the T500 chips. There is no need to use T25 /T100/T500 chips for re-buys or color-ups, as it is highly inefficient and a waste of money on chips that could be better spent elsewhere on the set.