@Harmon
#1 is of dubious benefit; an issuer isn’t going to give you credit for having an account with them that you never use.
#2 is just false. Closed accounts remain on your report for a minimum of 10 years and you get full credit for their aging over that time. “Average age of OPEN accounts” is not a real thing.
@Sterline
Doesn’t take much effort at all and it gives me the flexibility to PC them in the future to other cards. I only have 3 cards that I consider sock drawer cards though. One Discover and two Amex, the BCE and Cash Magnet.
I have a couple that I care about keeping open long-term in my wallet and use them whenever I have a random non-ApplePay, non-category spend, usually parking.
Depending on the card, it might be used for an automatic payment for a utility or the like. If it’s a cobranded card, then I’ll use it when I book a trip with that brand (Marriott, Southwest, Delta, etc.). If it honestly serves me no purpose, then it doesn’t get used. If it gets closed a few years down the line, oh well.
I keep a spreadsheet with last used date as one of the fields. I sort on that field to see what my longest unused card is. I also have 4 small repeating AppleCare charges. So I add the longest unused card to my ApplePay to pay the next AppleCare charge. ($4-6). Once it posts, I update the spreadsheet, then delete that card from ApplePay. Then add the next card on the spreadsheet, and repeat.
I make sure there is at least 1 charge per quarter. If I don’t have an organic purchase by the end of a quarter, I will just buy something off Amazon for less than $5 (you used to be able to buy Amazon GCs for $1, but the min is now $5) as I have Amazon Prime, so shipping is free even if it is a $2 item.
I put my recurring cloud storage subscription on it. $2.99/month so it doesn’t close.
I have a bunch of cards that are in my sock drawer. I’ve very rarely had any close without notice (FNBO is the only that comes to mind). The ones I care about the most are ones that have been open for the longest amount of time and honestly, I always get a letter in the mail giving me plenty of warning if I don’t use it by a certain date they’re going to close the account (BofA and Wells Fargo cards).
I currently have one card in my ‘sock drawer.’ It is one of my oldest cards from the bank I use with a relatively large credit line. I keep it open by putting my security system subscription on it.
If I were to have another card I wanted to ‘sock drawer,’ I would put my monthly $2 Google Play card subscription on it. (When I get my Citi Rewards+ card, this will likely be its fate after I get the sign-up bonus as I mostly want it for the 10% ThankYou points boost)
Just make sure there’s no fraud and hope that they get closed on their own 
.
I just have cheap subscriptions on them.
I put in a recurring Calendar event every 5 months.
Login to Amazon and reload $5 for each of my Sock Drawer cards.
I had 2 cards that were closed because of inactivity. They were store cards and my credit file is established enough that letting them get closed didn’t affect my score.
I have 3 open sock drawer cards that I keep open because of CL and these were my oldest cards. I set a calendar reminder that repeats annually to remind me when it’s time to use these cards. I would put them in my wallet so I can use them for next purchases, then they go back to sock drawer until the following year.
Chase and Amex Offers on the card means there’s usually a very easy way to use each card at least once or twice a year if not more.
I really only have 1 ‘sock drawer’ card which is the flat 1.5% card I got from my local bank and didn’t use much because I didn’t really ‘get’ credit cards.
I just have a $9/month subscription on that card with autopay turned on so I don’t ever think about it.
I got my first credit card, Wells Fargo Cashwise, set up with a $3 OF subscription.
It used to be Amazon, until they made the $5 minimum.
I don’t keep any cards I don’t actively use. I just close them, but I’m old and have a very robust credit history.
From time to time, I spread them out on the table and reminisce on the days I thought it was a good idea to apply and the reasons we don’t see each other that much. Sometimes I get to feel the texture and quality of the embossed cards and pray for the day the banks will close them out, 'cuz I ain’t got the time to do it myself nor do I care.
I don’t use it for anything other than balance transfers if I want. I haven’t made a regular purchase on that card in 5 years, I think? But they keep offering me 0% APR balance transfers for 14-month periods.
I ignore them. Haven’t had a single one closed on me.