I think it’s just like @Rook have said, everyone’s every card is different. That is, my dumdum Gunnar card is not the same as her “legendary” Gunnar card.
@King_Nothing
My Berden is definitely working out better than yours because he’s already 8/8 at level 18 of 3^ and Hawkmoon and Dawa both are the same way. My copy of Jahangir/Greymane are thus far not doing so well in that they are both just on the 2nd ^, and their specials 2/8, acquired by ascending once. Whereas my others have either gotten 2 or 3 before the first ascension.
The last time I tried to kept on maxing someone and for a long time was Layla (hey, I was new ok, and she was my best purple until I got Prisca). I was going to train feed her 4x Layla but she ended up getting special maxed before that happened during one of the the feeding sessions where I fed her other 1* and 2* purples, either one at a time or a few at a time. The completionist in me confounds me to max Gunnar out, even if I had to get multiple copies of himself to do it. But while I am waiting for the 8X Gunnar to arrive, I sometimes slip him a 1* or 2* just to see if I can shorten the amount of Gunnars I have to acquire, so far, he hasn’t moved.