Activator/Catylist/Hardner helps in dry times , and durability.
Its also an integral part of the primer or paint.

Bad things can happen with applying an uncatylized primer that needs catylist , then if you use a catylized single stage or the new base coat clear coats to top coat that uncatylized primer it may cause lifting, poor adhesion, and other bad news.
Then you get to strip it all off and start all over.

If a product requires a catylist, by all means use it , dont skimp because of the price as it may cost you a hell of alot more money and time in the long run!!

SprayTech