I'll take a modified bet on the quote above...
Agreed, you have to go higher than 220, but 1500 is unnecessary unless you aren't actually at 1500, but think you are. This is a very common mistake when sanding because sanding at any grit doesn't make it finished to that grit until all the scratches left by it are uniform. Knowing how to actually determine this is harder than you'd think, but easy to misjudge if you are skipping any grits or going up in too large of increments of grit.
The resolution of essentially all paint is much less than 1500. Even if you're shooting lacquer, you'd finish the paint itself to 1500, or more, but not the substrate before you apply paint.
When painting plastic, metal, bondo or other similar things, as opposed to staining or finishing wood, it can't hurt to go to 1500, but it can be a lot of effort for no benefit, so even if you think it's required, you're not going to harm your final product.
I work with almost every type of finish you can think of, on many different materials, but sanding prep is exactly the same on everything. Understand the finish requirements, and don't do any more prep work than necessary for your finish to be perfect.