I actually do the MS/MB rotation whenever SF is up regardless of DA. they do line up together often but not always. Holding either for more than a few seconds is not worth it though. It's still a DPS increase without DA active.
Many priests I know have been doing the MF ticks to allow orbs to generate before instant casting MB, but I have gotten better results personally with more hard nukes per cycle. The kicker of the MFs in the rotation of course being evangelism stacks for your initial dot re-apply after the burn. I have tried 5 tick MF after a burn that used DA but I just didn't see a noticeable difference as opposed to simply re-applying with ES only and no Evangelism. Since that fist round of dots without 10% isnt very significant. Plus if your doing the burn without DA mid fight then you dont have to worry about Evangelism anyway as it will stay up until you re-apply dots. it's only a factor after SF/DA combo burns and then only a small factor as the nuke phase makes up for more than the missing dots and a single round of less buffed dots.
Oprritunity cost seemed high to get 5 ticks of MF and lose however many dot ticks. As stated though this is by no means the end all be all MS/MB rotation just the way I have found that works best for me
Thanks for the feedback guys.
@Felade I wouldn't hold for WoU since as you said your other procs will start to fall, but also the tinket will be fully stacked toward the back end of your burn regardless as you should be getting 1 stack for a pre VT plus 2 stacks from your Mind Flays. You should get 11-14 casts with SF active depending on haste/buffs so upwards of a third to half your burn could have 10 stacked trinket.