Besides the fact that lacquer is outdated junk in todays paint world, It is possible the harsh solvents in the lacquer could wrinkle and lift an enamel or urethane product if it is applied over an enamel based product that hasn't cured enough. One of the things they taught us was enamels could be used over lacquers but lacquers not okay over enamels.
Many seem to think lacquer is cheap and easy so it makes it a good idea. But when you think about how much better and the greater film build of a 2k urethane, which can be sanded in a reasonable and normally sand realitively easy, and will have less shrinkage then a lacquer, I think the urethane is a better deal. Back in the years I used lacquer, I've had a few instances of bullsyes show up in the paint around repair areas, never once had that using a urethane. Sure lacquer can easily be found in a spray bomb, but if the lack of equiptment is the reason you are using spray bombs, you really should get the proper equiptment and not take shortcuts if you want to produce good long lasting results in the body and paint area.