Liandry's Torment: Dumb question that's probably been answered already

If you were to movement cc someone, and then hit them with a spell while you have Liandry's Torment, if the burn (3 sec) is longer than the cc itself, such as a 1 second or 1.5 second stun, does the normal burn 6% of max health (because 2% per sec for 3 sec) only burn for double on those few seconds where they're considered to have "inhibited movement", or do all 3 seconds burn for the maximum of 12% of max health (4% per sec over 3 sec)?

To make it easier to read:

Does one cc ability give you all of the burn?

Or does it only give you a small amount of burn for one or two of the seconds of the Liandry burn?

Just asking because I feel like I don't feel the Liandry's health scrape effect as much as I'd like to. Sure, it's great for the mixture of mag pen, health, and AP, but I'd rather not have a "we buffed Syndra's orb hitboxes, except we didn't" kinda situation again.