These are just my opinions.  The less you wax the better.  Every time
you rub the finish you put  very small scratches in it.  My 92 paint
still looks almost new because I don't wax it, I just protect it from
the sun.  If you are going to "wax" I think the liquid is better
because it takes a little less rubbing/pressure to apply and remove.
I've always heard that multiple coats are pointless because wax only
builds up to a very thin amount and additional coats just remove the
prior coat.

All that said, if you can't protect your car from the sun and
pollutants it's probably worthwhile to use a once a year wax and as
the paint becomes more and more damaged you may have to wax and/or
polish more and more often to get some shine out of it.

==========
This isn't exactly what you asked, but over the last forty years I've
tried a lot of waxes. My favorite is Zaino. Not the lowest cost, but if
you read and follow all their instructions you wind up with a finish
that just gets better and better over time. I used the Dawn, clay bar,
Fieldcrest towels, whole process and then just used their wash and wax
weekly for the last couple of years. I can usually spot my car in a
crowded parking lot simply by the gloss even though it's  a 1994. There
are no abrasives in it so it can be layered. Very slick, very smooth,
very high gloss, UV resistant finish that I initially applied because I
could see the beginnings of color fade but now the finish is so glossy
you can't really notice it anymore.

This is by far the best and longest-lasting I've ever used:

http://malms.com/

Their Ultra-Fine Polishing Cleaner is also very good.