I've tried the no pest strip, but it was over 20 years ago. Now I just use water dips if I get mites in flowering. No pest strip works, but you have to seal the room and put a circulating fan on the strip to make sure the nerve gas or whatever it is gets distributed. Problem is, to get it to work is a high dose, and it will leave a residue. I wouldn't use it on flowering plants at all, only in veg if ever.
I'd recommend learning to water dip. It's very effective and totally 'organic', but you have to keep dipping once a week or so 'till harvest because straight water doesn't knock off the eggs too well. You can also double dip, once in a soap and/or neem solution then water. Double dipping takes twice as long, but it gets the eggs and can even wipe the mites right out if you follow up with a second hit in 3-5 days.
Even big plants up to and beyond 5 gallon containers can be dipped with two people. Use a 'trough' container for the water like a big cooler or rubber maid, or even a bathtub. One person holds the plants pot and lowers the plant to about horizontal above the trough while the other person shampoo's and pushes the branches under water. Take your time and be sure to smile, the mites are having a very bad day.
"My dream is a five pounder at the end of every cul de sac in the land!" Mr. Greengenes