NO, why? If you are useing quality jhp then no need. If you are useing an underpowered round then just use fmj. I know some flip slugs and buckshot in thier shotguns but a hand gun is not a shotgun.
I would be afraid of a jam.
I don't. I've never heard of the practice discussed positively by trained shooters or instructors.
IMHO if you really need 2 or more types of ammo (most applicable to military rifle use rather than a carry pistol), then keep separate mags and choose the proper ammo for the job.
Never. About the only ammo mixing I do is 3 rounds of tracer at the bottom of my AR mags. I always keep my slugs and buckshot in separate mags and the same goes for a mag full of AP for my AR. I don't even bother with a mag full of FMJ for my pistols.
I wasn't stating that I condone this practice, I don't. I load hollow points in my CCW. I was just curious if the alternating rounds theory held any water.