Back when I lived in a humid environment I would do a quick wipe down of the metal parts of my new mags with a product called Prolix. Then let it sit a few minutes and wipe off any excess. It is supposed to clean and lubricate but it doesn’t do the greatest job at either of those. Though it works perfectly fine on for keeping my Glock pistols running. What it does do really well is prevent rust and crude build up making things easier to clean latter if needed.
Other than that I usually only give the feed lips and follower a quick wipe down every once in while.
Thought I had my first dirty mag related failure to feed last weekend. It was during a reload with a partly loaded 15ish year old very cheap Korean made KCI mag for my G19 that I have never taken apart to clean aside from the initial Prolix treatment. After I emptied the mag I could see that the follower was getting hung up and assumed it was due to powder residue or dirt. Made me think it was time to finally clean all my mags but when I took it apart I found a piece of plastic that was sticking out along the edge of the metal lining. Filed it off and the mag works fine again even though the spring is really weak due to the countless number of rounds I have put through it.