Unpainted wood and drywall can pose huge adherence problems for coatings without primer. With fresh drywall, the substrate actually absorbs a coating really well, like a sponge. However, because it absorbs so well, without a primer coat, you'll experience uneven coverage, especially along drywall seams.

No, there isn't a limit to how many times you can paint your wall.

The 24-hour drying time recommendation can be applied to nearly all factors. Some manufacturers will bring down that number to 12 hours if a few shortcuts are applied to help speed up drying time without affecting the finished product. Filled-in screw holes and minor indentations can take about 2 hours to dry.

Before painting, it is common to repair or patch the walls with some spackle or joint compound. If these repairs are small, you do not need to purchase a primer but apply a light coat of your regular paint on those areas once the spackle or joint compound is dry.