Kim ~ I have a theory about this. It's not rocket science. The only way for them to "get over" OT is if they get more sleep. Just cutting down A times and squeezing in 2 naps isn't a guarantee this will happen, though for some LO's it helps, I'm sure. Not so much for Tara. When Tara is OT, I can cut her A times by 15 minutes, that's all, because if I try more she gets into an UT/OT loop that doesn't solve anything. And giving her 2 naps means I have 3 A times to factor in, which means less night sleep. If your LO doesn't sleep much at night and just flat out won't, then giving him an early BT probably won't help him catch up. Although as they get older, they do learn to sleep more at night and less during the day. Gradually.
What Sian mentioned actually does work pretty well with Tara. A little OT, she's fussy, wakes early from naps, etc. But at a certain point she actually does start sleeping more to catch up. I'm not so scared of the OT build-up because I know from experience she has a sort of "reset button." I'm sure not all babies do this, but apparently some do. Somebody said (I wish I could remember who) that spirited babies sleep well when their A times are just right or waaaaaay too long. That's Tara. A little OT is bad, but a lot of OT is actually good, because then she starts to sleep well again.