SharkBite

Is it better to do a section at a time, like say a fender (add, let it dry, remove) and then move onto a different section, like the door or is it better to do the entire car with wax or polish, then go back to the beginning and remove it all at once?

DTN

It all depends on the style of wax that you use. There are two styles of wax; wax that hardens and wax that does not harden.

With wax that hardens, you need to do one section at a time. This style of wax basically goes on, then you wipe it off before it hardens fully. After it hardens it forms a shell, which also makes it difficult to rewax. The shell stays on the vehicle for a long time and will protect the clear coat. This style of wax includes carnuba and urethane based waxes. The urithane style wax tends to stay on the car for a longer period because it has some plastic quality to it. The carnuba based waxes tend to leave a better finish but do not last as long.

With wax that does not harden, you do the entire car. The idea is to give the wax more time to stick onto the finish and seep into the microscopic crevaces in the paint. With this style of wax, you will get a much shinier result and shorter results. The two main types of non-hardening wax are "wax" and oil based. The wax based tends to last much longer with less shiney results. The oil based lasts much shorter with more shiney results.

Here is the duration I expect out of each of the styles of wax I mentioned.
Urethane- 6 months - good for winter
Carnuba- 2 months -good for lazy people during summer
wax- 1-2 months - overall best shine and renewability
oil- 1-7 days. - best shine, but good only for a car show or event.