I guess a heavy coat is always subjected to getting runs. There's a fine line between a good coat and a coat full of paint runs.
Yes a mist coat (dust coat as it's normally referred to)and then a medium flow coat, then let it go off for about 15 minutes and follow up with another decent final coat.
A lot of spray cans are full of nothing more than a bit of colour and a majority of thinners to make it go off quicker, thus the coat is far smoother due to a lack of paint solids that give you the build up, thus why I use a gun and mix my own.
Cheers,
BB.