I spray my plants once a week with Neem, with a pressure sprayer..just blast the heck out them, tops and bottom.
However once buddage starts forming I just use water and use it sparingly. Last 4 weeks of flowering..nothing but a rare light misting.
I live where it's super dry and mold has never been a problem.
But I grow in a tent and would never use Neem as catchall in an open room. In the end you'll lose ( or have a constant fight on your hands ) until you can seal it up.
And just before flowering I blast them again with Neem....seal up the tent and throw a Hotshot No Pest strip in there overnight ( and again a week later ) and never have to worry about bugs again.