I agree with the descent planning advice of Wizofoz. You either need speedbrake or you don’t, the intermediate position will only give you all of the noise for little of the drag and twice the roll rate…
The answer is in the FCTM page 4.18. (31 Oct 2003). Descent – Speedbrakes
“Use of speedbrakes between the down detent and flight detent can result in rapid roll rates and should normally be avoided.”
S & L