if the surface is clean and polished, leaving it on for longer periods should not make it harder to wipe off... (although I remove as soon as it appears dry myself)
It does make a difference some times as to the product you are using.. Most use "Polymer" sealants and some still use "wax" Read the container and follow their directions.. they usually know what works best for the product..
I owned a couple detail shops in Mesa AZ and found that even in AZ, a "good" carnauba wax worked as well as most of the polymers for shine and life.. The carnauba waxes are just a bit tougher to apply (machine works best IME)..
The polymer sealants tend to wipe on , wipe off.. The "high solvent" cleaner waxes are really nice but only last 1 or 2 wash jobs (used mostly for new car prep)..
a couple basic DO NOTS:
Do not wax a dirty surface (seals in crud)
Do not wax a "hot" surface (can discolor or blemish)
Do not wax in the sun (same as above)
I would suggest washing your paint at least twice before using the first application of any sealant... amazing how much dirt is actually on the paint in most cases after the first wash..