I was not there but results kind of speak for themselves.
Improper reducer speed for temp.
Low grade reducer.
Improper flash times between coats.
Piling on base to fill imperfections.
Or just took to many coats to cover and that requires more dry time.
Perfect example, I started painting the vette Saturday, laid two coats of VW silver activated base.
Sunday morning I laid first coat of blue ink coat, let each coat flash of exactly 60 minutes and all coats were activated, it takes four coats of the ink coat to hide, so I did five coats.
Plan was to let set 24 hours, wetsand base with 800 and shoot one more coat of base and clear.
Monday Morning, found two imperfections in base, spec on fender and spec on deck lid, did not want to sand base yet but did take some 600 wet to one spot and sanded OK but base was not totally cured yet. Tuesday night base sanded like a dream and will finish up tonight. The more coats, longer to cure.
Now do keep in mind this is no enamel converted crap base, its one of the best and we still have two days.