MT (in one of the Journals) has a picture sequence of the process of donning battle dress. It's about as onerous and entering a space suit nowadays (maybe a bit faster, but it is a team event, although you could automate it with some bots). I doubt this is shipboard dress for most marines NOT expecting to be in the middle of a battle. I think that would be some sort of sleeve with some armour properties, some LBE, some inherent life support (and with the ability to snap on more, ditto with armour), and some sort of light weaponry - likely laser rifles in case of zero-G. If they were ready for a battle, yes, the Marines are broken out with full battle rattle - battle dress or combat armour, FGs and PGs, etc. But for just day to day, no.
If you get multiple 20 minute high guard turns, breaking out the Marines in full kit is possible, maybe in 1 turn on a good day, 2 on a bad.
But if your foe jumps in on you or ambushes you in some unexpected place, your kit is your usual duty vacc suit/sleeve and whatever weapons are available without heading to the main armouries (sidearms or rifles from individual hull section arming stations). Some portion of the Marine unit would forgo reporting directly to stations so that it could get in full battle rattle and be the fast response team.