Don Rapidly
Modern clothing is pretty easy to get on: T-shirt, jeans, socks, and potentially underwear. The hardest part of my wardrobe is the tie. Even then, getting dressed pre-coffee takes me several slow minutes as I grumble about the cold. I can’t imagine having to lace on invidival legs of hose or fumble through donning numerous layers of intricate interlocking bits of armour atop padding. Donning armour feels like it should be a three or four person job that takes fifteen minutes. I’m sure that after a few attempts it’s quicker, but it still can’t be easy.
Having tried different armor types (in real life) I’d say it largely depends on the kind. Wearing a brigandine or padded armor takes just as long as putting a latched winter coat on (the longest part being the tying of knots to close the front).
donning a banded mail (the type used by Roman legionnaires) takes about one minute, less if someone helps. It is also very comfortable ad surprisingly allows for the widest range of movements, despite the 12 kg weight. You just lift it above your head and fit in from the bottom (it doesn’t open on the side). Wearing a chain shirt takes about the same time, while for a 16 kg, full fledged chainmail (with leggings and long sleeves) at least 3-4 minutes are necessary. Add another minute for leg greaves.
I’ve never tried full plate, but I witnessed people donning it… 5-10 minutes (depending on the model) with a couple of aides are required if you really want to look like a stove.
Japanese armor would take the same time, being lighter but similarly composed of many pieces.
About armor removal, it takes longer for the banded one, while there’s a swinging movement (while looming forward) that lets you drop a chain one in just seconds (provided you removed the belt first).
As many other things, it is mainly a matter of practice.
And THAT is why I like to play as Barbarians! (And run sword & sorcery-themed rule systems that supports warriors dress like they are posing for a metal cover.)
Just strap on my armored cod-piece (or metal-bikini)…
Oh, who am I kidding? That would just weigh me down! (and so liberating!)
…then quickly pick up whatever I have at hand, and make sparks, screams and crimson fly in an orgy of mindless slaughter! (And neekid bits!)
Who needs gantlets whet you have a fist full of rings? Who need a helmet when you have a head as… eh? err…? What was I talking about?