Last Phase of Tapering: how much Time to take?

I'm wondering just how slow the last phase of tapering should be, and for what reasons.

A slow taper should give the cns time to readjust to smaller doses and start uprelating GABA-A receptors. According to my pharmacist, this upregulation is supposed to happen in a hyperbolic way. So the dose reduction near the end has much more effect than the same reduction earlier on. A constant relative reduction, say 5-10% of current dose each couple of weeks, would serve that purpose just fine.

Still, making those small cuts when already on a low dose, could prolong the process substantially. The Ashton manual suggests jumping on .5 mg diazepam or its equivalent. So how slow should we go below 3 or 5 mgs diazepam? Does it matter what the start dose was (the manual does not suggest this)? And would it be wise to have a really slow taper like 2, 3 or even more months for those final 3 mgs? FULL healing needs stopping altogether, but could a long last phase prevent severe sxs in acute? I look forward to your input, from experience or just your ideas.