Dounoharm, glad you see you follow instructions when you don't spray all the time preventively for nothing save intoxicating yourself
but you should tell the thing in full. (All right I'm pushing you a little, sorry for that, but I've read your posts lately and I think you do spray too much, please don't hug me afterwards.
Here (France) we don't have full routines just general direction depending of the product usually not going beyond the interval between applications. Routines are only in agriculture, with products not available for the rest of us (fortunately).
An alternate scheme should be avery 2 or 3 sprays, yes. And there's nothing written in marble.
When your treatment isn't effective manifestly do not stop! Wait a few days then treat with an alternative and have a spray schedule along those lines: (e-ffective, i-nefective)
i-e-e-i-e-e… or i-e-e-e-i-i-e-e-e… to keep the pressure on the pest. Use the intervals as written on the bottles (time before next spray = schedule of the sprayed product). Anyway, most molecules make a long stand in the plant (in the 80… 160… days) and the usual 10 or 15 days delay is the time it's at full force in them. When you alternate, you have after the 2nd product both molecules at work, and even with resistance to one, greater pressure on the pest, as if it can easily adapt to one threat, fighting 2 even if resistant to one is next to impossible (note the "next", resistance WILL occur one day for both).
To help, you can use nettle manure (diluted at 2%, my way, or at 5%, SFO way) as repellent and defense fortifier, or tansy manure (insecticide and repellent). Mealies don't like this at all. Note that manures are slightly fertilizing, especially nettles, and it's a bad idea to pump plants natural defense all the time so don't use them, give plants some rest and treat only when needed for these.
Think about those living in the pot, a dive of the pot into a solution of 3 teaspoon/liter of alcool AFTER your watering routing for half an hour will destroy most of them (the etched, not the eggs…), rinse afterwards.