Does it happen to everyone?

I'm much the same. I've two spare Nephenees and I fear foddering off such a rare skill in case a new unit will use it better. I'm thinking one will go to Soleil so the other will have to stay until another appears as I don't want to have no Wrath.

It does'nt really happen to me much since I use every 5* unit I get(though some warms the bench longer than others but I still use all of them)
From what I can see(and just assuming that she does'nt have it) give it to Lucina.
Dragons like Myrrh and the Tikis(if you are gonna use breath of fog) are good candidates.

Armor units that don't have innate dc. Effie,Sheena,Gwendolyn,Draug.

Any of the teir 1 units(in arena offense teir list) can work with DC.

or just keep Hector, but I'm gonna assume that you don't like hector that much so you might not use him either way.

I never foddered any 5* for another 5* unit, it's hard for me, I don't want to regret my choice later ... And I don't know how to use some of these exclusive skills. For example, I have two Dorcas and S!Xander, but I don't know who to give infantry pulse. xD
DC can be great on Myrrh or on an armoured unit who don't have DC. Personally, I think I will fodder my second Hector for Effie, she is already +7 and she helps me a lot in the arena. ^^

Same to me. I have kept my 2 extra Lyns and 1 extra Bike for months, and many more premium fodders like H!Henry, W!Tharja etc. But I went all out just now and butchered off 5* exclusive units (W!Tharja, Hector, Hardin, H!Henry, Bike), and a few more 5* which I got previously (L'Arachel, Chrom, Berkut) because it is just too inefficient this way. I can never get closer to T20 if I don't do this.

I must admit, it was quite refreshing seeing the barrack being cleaned nicely.

Who to have DC? The answer is always Soleil.

It isn't even just other heroes. Just days before we found out that Heavy Blade was going to be a seal I sac'ed an Ike for it. I was not particularly happy.

Well, saving up great fodder is not nessecarily bad. You just have to be clear on what your goals are.

For example, I've been sitting on Bold fighter, Steady Breath, and even DC fodder for a while, because I am still theorycrafting my three arena cores. Eventually, I want to be able to rotate cores to stay in Tier 20 and try for top 1k AA. So giving Steady Breath to, say, Adult Tiki, would bring me further from that goal (her BST is simply too low).

Happens to me!

For a long time I was hanging on to an extra Karel for Wo Dao. Only decided during the fangs tempest trial to merge my old Karel into him instead of feeding for skills. Now that he's gotten more SP from leveling up to 40 again, he's actually pretty darn good.

Still have two copies of Celica, three New Years Azura, two Nino (regular), two L!Robin (F!Grima), two Faye, two LA!Roy, three B!Lyn, two P!Olivia, two B(ridal)!Lyn, two H!Henry, two C!Chrom.

Decided to level up all my Brave Lyns for an all B!Lyn cheese team. I managed to merge the 5*s that have nothing to inherit, like Seliph. Other than that, complete and total indecision paralysis.