The expiration date for temple ordinances is NOT helpful as it doesn't give enough time to get the ordinances done.
How much time do you need?0
The point of the expiration dates is to get ordinances off of your personal list since you don't have time to do them, and onto the shared temple list where someone may have plenty of time to get them done.
There is no need to take 90-ordinances away from the general temple list where anyone can complete them unless you can complete them within 90 days.
The goal is to get the ordinances done rather than have them sit on reservation lists for years on end.
If there are ordinances you have reserved and would like to do when you have the time, just store them in your shared with temple list. Then be thrilled when a relative, near or far, finds them and completes them for you.
If there are ordinances someone else has reserved and shared with the temple, that is, 90-day ordinances that you would like to do but are afraid you won't be able to find them again in a couple of years, copy the URL's of the people and past them into a text document. Then when you are able to complete them, use the URL to find the people and see if the ordinances are still available or if one of your widely extended family took care of them.2