i find a few invaluable at high levels when you face mobs that require multi holds to get them rooted, a purple boss that you just missed storming towards you is not very nice
then you have the AVs where if you miss a hold then you have to start all over again
also depends on you power set i found illusion had phantom army wich could be cast into a group to hold aggro , but my new ish troller has a single mez, grop hold , group mez, pbaoe mez and a long range pb aoe mez( mez for me = they cant attack , hold = cant move )
wich means i pretty much have something to cover my [censored] if an ambush jumps me
I use 1 on my Fire/Rad for PvP.
2 Acc, 1 Hold, 3 Recharge.
I have two in all my mez, holds, fears and confuses but i'll be dropping some down to one since like you said most mobs are dying now before the hold runs out.
Personally i'd look at all your powers and judge each on seperate, Perhaps keep two hold enchance in your AoE's and drop some on your singles.
Now @Eskimo-Spy
I'm not evil.
Yeah that sounds about right. Good to know some others feel the same about this. 3 Recharges is definitely the way to go for the single target holds.
But I guess this is actually more a team-oriented thing, for solo 3 holds might still be best - I don't solo a lot with my Controllers tho.
3 recharges opposed to 2 gives roughly half a second faster recharge on your single target hold. Personally I don't think it's worth it so I'm going with the classic 2 acc, 2 rech, 2 hold dur
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Against normal mobs 2 hold would probably do but for the tough enemies which need stackable holds 3 is a must.
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3 recharges opposed to 2 gives roughly half a second faster recharge on your single target hold. Personally I don't think it's worth it so I'm going with the classic 2 acc, 2 rech, 2 hold dur
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Finally a voice of reason 
I've found the more I play controllers I don't actually need 3 holds, or even 2 sometimes - especially, the higher up you go in the game, the quicker the mobs fall anyway, and in fact it's more useful to have more recharges in there.
Any other Controllers find this?