Makes perfect sense. For a particular type of hardware, some projects run much more efficiently than others. Still worth checking again in future, as credit levels can change appreciably over time.

You do this for badges?
Might I suggest you reexamine your motivations.
One of the most inspiring people I ever met was a kid by the name of Steven Hunter. He had MD.
He was at the stage where he could still walk but at times his legs would fail and he'd fall flat on his face. Never hear him complain, just pick himself up and start walking again.
You meet people in your life like this and they make an impact on you.
I haven't seen him in 25 years but I'll never forget that kid.
Think on this a bit and maybe you'll understand that sure the little icons are fun but they are just small symbols that in reality mean nothing.
The work is all that matters.

Who cares why people do it. They're still doing it.
They're paying the extra electric bill and donating their machines to multiple efforts. Thumbs up to them.

While I'm also guilty of working for the badges. I do have my favorite research projects.

I look at any work I do on the others projects as helpful.