Eh I already gave the math behind CR decay and how it affects the Hyperion
here, not sure why a video or a new thread needed to be made for it. The testing is easy enough to do using a Heavy Blaster (which fires once per second) or whatever other weapon you want to use as a timer; it's important to use something on the game's own internal timer (such as a weapon) rather than an external timer because the two may not sync up for various reasons. And indeed it's easy enough to see that you get exactly 4 Heavy Blaster shots for every 1% of CR decay normally, but if you have both Combat Endurance and Hardened Subsystems then you get slightly more than 7 Heavy Blaster shots for every 1% of CR decay, etc., in accordance with the math.
Or I guess you can just sit through a video of the whole duration if you don't want to follow the math.
Now since a Hyperion gets 40% CR taken off
after combat, and there is no negative CR as far as I know, then once it reaches 40% CR, it won't cost you any additional supplies for recovery to keep it around in combat, as long as you don't lose the ship (in which case you pay in d-mods, etc., but the supplies cost is the same). Actually if you have Field Repairs (recovered ships start with 30-40% CR) and Hull Restoration (chance to avoid d-mods and repair them over time), I wonder if it might actually end up cheaper supply-wise to intentionally destroy high-CR ships like the Hyperion once they hit 40% CR.
It's a definite risk of losing the ship once it gets to malfunction territory though, so it's something to consider depending on the situation (i.e. maybe if you're already mopping up for example and don't feel like deploying another ship, then go ahead and keep malfunctioning ships around since they cost you no additional supply), but not something I'd recommend as a general combat strategy. For people who don't mind losing ships after big engagements or considers it an achievement just to win even if they lose multiple ships, then maybe this isn't such a big deal. But for people who prefer to set up their fleets so that all their ships survive (i.e. don't rely on Hull Restoration for example, which severely limits how much they can invest in the other combat trees), or don't rely on burning their whole fleet's CR down to the ground for each big engagement as a combat strategy, then there are much more efficient alternatives.
For example, it takes 50 supplies to restore each Hyperion from 0% CR to 100% CR (if you include the regular maintenance cost of 1 supply per day during that recovery period as well). An Odyssey which ends up winning the fight without dipping into CR decay would cost you 52.5 supplies, so you're paying practically capital-size upkeep for each Hyperion that relies on that kind of combat strategy.
Generally speaking though, when people discuss how long a ship can fight, they're not talking about taking it down to 0% CR, due to malfunctions. Generally it's assumed that the ship is heading out of combat once it starts getting below 40% CR; in fact the risk of malfunctions is the game's way of warning you that you should consider retreating that ship. The Hyperion happens to be a special case due to its high CR per deployment, but it still risks malfunctions and dying just the same.