Well I found out the hard way when I put a new kitchen window in upside down and it rained inside. The reason was there are drainage holes on top. The caulking I inspected on other rigs was always on the top and sometimes on the sides but never on the bottom as it traps water.
And yes it was me trying to be mechanical and I almost fell off the ladder and did put it on upside down. So luckily, since I used plumbers putty, it was pretty easy to correct. Almost tiiiiimmmmber..........