I have worked in the aerospace industry for almost 30 years and ALL of our caulks and sealants are always stored in a "cold room" until it is given out for consumption, so @ home I keep my caulks, glues, & sealants in my shop fridge in a ziplock bag, works great. YMMV
Questions like this always amaze me when they come up. They are ones we all have and most of us just keep putting up with and don't give a thought to asking someone else if they have figured out a solution.
I agree with Chucky. The stuff at work never has the cap on because they always get lost by whoever last used it. Take off the gob on the end and all is good. On the other hand, I always replace the cap at home because I 'm afraid that if I don't, it will harden. As a result, my own hardens and I'm left wondering why. Time to become more careless at home.
I ran into this problem and came across a solution on the HAMB board many years ago. when you've used the product and still have some material left in the tube, before you store it, suck a little of the RTV back into the tube; just enough to form a little pocket in the tubes opening. Then put a small amount of grease (I use axle grease) into the pocket sealing off all air to the uncured RTV in the tube's opening and then replace the cap. Make sure that you get the grease filling the whole void all the way to the edges. When you need to use it again, remove the cap, squirt out a little of the RTV to get rid of the grease-contaminated material and apply as needed. I've done this for years and have opened up a used tube where the RTV is still soft after well over a year's storage in my garage (definitely not climate controlled!) with no problems.