That is a fair point. While we could only assume that they were time limited (since there wasn’t any way to know for sure), I imagine many considered it a possibility and sped through them because of it.
I myself left nothing to chance and completed as much as I could during Season 1, to avoid me losing out on limited-time stuff. Completed 160, got high rankings in all categories, maxed out all weapons and classes, and did all Okri’s Challenges.
But even if the “complete 40 missions with x class” were added to the general tab now, and we knew they weren’t time-limited, I would still choose to speedrun them. The main problem with these kind of challenges is that they rely on the gamemode actually being fun. With all the current problems weaves have (High Ranked Weaves Gameplay Feedback (120-160)), as well as the fact that weaves are static and have very low incentive reward-wise (outside of ranked), I don’t think these kind of challenges would be a good addition to weaves.