the biggest problem with the shopline clear is the level of solids, the part of the clear that actually stays on the car after it'd dry, is much lower than 2021.
2021 clear has 42% solids, ready to spray when mixed with DCX61 catalyst. 42% solids 58% of solvents that will evaporate away.
i don't have the tech sheets on the shop line, but if i remember correctly it has about 15% solids ready to spray. 15% solids 85% solvents that will evaporate away.
these statements translated into understandable statements is basicly 1 coat of 2021= 3 coats of shopline clear.
this is why the shopline clear doesn't have long term durability. this is also why it is MUCH cheaper than DCU2021.
when i spray shopline i usually spray 5 coats of clear. bake and dry overnight. sand with 1000 grit then respray 4 more coats of clear and bake again. then sand and buff 2 days later.