It all depends on where your doing the job, if you have a booth to use then it time doesn't matter, but using base/clear you obviously do more layers than using 2pac/k so you need more time Inbetween cleaning/prepping/tack clothing, where as 2pac uses less work as the coats go on heavier

Either way I'd recommend 2pac primer/hardener as that goes on really tough, and protects the top coats from reacting to anything a panel wipe don't remove