I'm thinking first 5 stealth, Scientist and SCRS loud, then either tactic for BD. Does anyone have a better strategy?

For BD, loud takes a bit over 10 minutes while stealth takes a bit over 12 minutes.

Just try to complete the mission quickly in stealth, and then go through the same mission loudly.
Im genius

hmm, I'd go for first 3 stealth, lakehouse loud, as it's faster, withdrawal stealth, scientist & scrs loud and black dusk loud.
you could try blacksite loud, but it's comparatively slower/faster depending on your skill on the map
good luck

Stealth first 3, loud lakehouse, stealth withdrawal,loud the rest

Alternatively you could also loud financier because on legend, the rng could just be insane and you would have to restart and average time on LLS financier is about 4 minutes.Sub 4 is possible of course

Regarding BD, loud it. Stealth is too much rng no matter what. Most efficient tactic would be:
Blast doors.Yes they are alot faster than current methods.
Ops>Workshop>Dev
Blast door ops, get thermite,blast door workshop, while workshop is thermiting, blast door/ vent dev (any is quite good MAKE SURE TO USE DRILL FOR THE VENT COVER IN VENT DEV,ITS THE FASTEST ONE) If you picked to blast door dev, wait until it opens so units won't get it.Then run straight back to workshop,plant bombs and run to dev. You should be at 8-9 minutes.The rest is quite straightforward, plant bombs and rush onyx. Get to dev vent as its the best spot and just kill onyx.If executed perfectly or modified to be faster.Bd could be sub 10

Blacksite: Stealth, loud is out of the question
Financier: Loud, much more consistent (3:30, use no armor and 2 med, it's not that hard)
Deposit: Either (4-5 min each)
Lakehouse: Stealth (loud is only faster duo+ smh!)
Withdrawal: Stealth, loud is out of the question once again
Scientist: Stealth (with luck 5-7 min)
SCRS: Loud, man this one's going to suck. (6-8 min)
Black Dusk: Loud (9-10 min)