No problem unless very old! I had an SDO that was a year old before I finished it. In a dark not too warm place kept vertical they should be good. For the last bit, I double pre heat leave it do a single reheat and pull away. If you are nimble fingered you can suck out dregs and squirt into another using a wide bore needle and syringe, but I do see that some MC carts do not have a removable mouthpiece.
Received one of these from a batch expiring 4/8/26. It now uses uses the CCELL EVOMAX ceramic cart, and is miles better for it. Flow is more consistent, taste is cleaner.
Clearleaf® Rosin carts were great before, but now they are excellent. My only complaint is that they go OOS very quickly because of this!