Keep in mind I build small...1/2A. Non-taughtening dope will shrink the tissue, just not very aggressively. As long as the tissue is wrinkle-free at installation/application time, and snugs up when water-shrunk, then it should snug up just a bit more later as non-tautening dope is applied.
On a couple of my models, the tissue sagged upon initial application, but then tightened back up over night. Another application, and it tightened back up over night again. After a few cycles, the tissue will have enough dope that it won't get so soggy on subsequent aplications of dope, so the bagginess stops. I notice this most on the models I use gift-wrapping tissue on. The behavior isn't as extreme on models covered with "real" model tissue since there is a grain that can be leveraged for it's shrinking properties.
My worst offense was in my 1/2A Mosquito...I need to post the damage on the RCG thread for that one. It looked good on initial papering. But then it bagged during the sealing phase. I got too "ambitious," and really laid the dope on. Each coat bagged...a little less each time. The last coat didn't change much beyond the previous one, do I stopped for the night. The next day I checked hoping to find tissue drum tight...which I did see. But it also curled up the trailing edge of the outboard wing! Patience would have gone a long way on that one.
I may try to mix non-tautening with tautening hoping for that middle ground between a sloppy bag and a Pringles chip.

Keep in mind I build small...1/2A. Non-taughtening dope will shrink the tissue, just not very aggressively. As long as the tissue is wrinkle-free at installation/application time, and snugs up when water-shrunk, then it should snug up just a bit more later as non-tautening dope is applied.
On a couple of my models, the tissue sagged upon initial application, but then tightened back up over night. Another application, and it tightened back up over night again. After a few cycles, the tissue will have enough dope that it won't get so soggy on subsequent aplications of dope, so the bagginess stops. I notice this most on the models I use gift-wrapping tissue on. The behavior isn't as extreme on models covered with "real" model tissue since there is a grain that can be leveraged for it's shrinking properties.
My worst offense was in my 1/2A Mosquito...I need to post the damage on the RCG thread for that one. It looked good on initial papering. But then it bagged during the sealing phase. I got too "ambitious," and really laid the dope on. Each coat bagged...a little less each time. The last coat didn't change much beyond the previous one, do I stopped for the night. The next day I checked hoping to find tissue drum tight...which I did see. But it also curled up the trailing edge of the outboard wing! Patience would have gone a long way on that one.
I may try to mix non-tautening with tautening hoping for that middle ground between a sloppy bag and a Pringles chip.

Thank you Jim.

I applied the tissue damp and let it dry and then started doping it.

You might want to try applying some on a test panel -- most tissue-tissue goes on dry, sags with water, and then shrinks up nice and tight when it dries.  To put it wet onto anything but a really curvy surface is to risk it getting too tight.

It sounds like you met with success, though, so that's good.

Did middleweight tissue cover job last night .

Atomiser bottle water on wing tissue , goes taut . Tailplane threw it on dry , then sprayed . Ten times the slack , damp .

Thus , it could vary . a coat or two of tautning / shrinking . At least on the open - tissue bays . BUT the starved horse leading edge sheeting
and uneven fuselage , from salubrious latherings , with the shrinking .

Still get visions in the minds eye of someones small scale rubber shrunk crocked deformed thing , from the youth .
Was a pre coloured all sheet Piper Cub available . No Dope required . Threw a slot car motor in & used it electric round the pole .

ON THE OTHER HAND , the P-51 covering , while smooth , is not tensioned on the open bays . Where I used Non Shrinking exclusivly .
Throwing multi coats of shrinking on anything in a short time , is likely the shrinkage will make a pgs breakfast of it  tho ,
Im thinking one or two coats , of the six or eight , could be tautning . Pref just aimed at the open bay tissue areas .

CAPPING STRIPS im pre dopeing & block sanding with NON SHRINKING . With no bothers wotsoeva . Undoped as per olde pomme advice they stick out like a sore thumb .Even 1/8 or 3/32 ribs im using a pin striping brush , about five coats ,and a plank sand with 180 / 220/240 .

Spraying the first few coats , drish , so theyre not ' WET ' to avoid the covering pulling into around the rib edge . Seems entirely succesful so far .

Getting good tissue here in Aus. is somewhat of a swine these days .