I replied to the other thread before seeing this. I’ll paste my reply here (and delete it from the other thread).
A better comparison is to blood moves. Both require staying alive on the battlefield for a while, both get reset by a repulse, both are the secondary part of the moveset (always plan A, and then survivor/blood). The difference is that one has the requirement of getting kill(s), but on some monsters it can be done faster or very reliably.
So basically survivor is kind of like bloodthirst, a move we rarely complain about a monster having!
It’s true there are a bunch of old monsters who have bad moveset + survivor, but the fault is with the rest of the moveset being super lacklustre. We have more modern monsters like Bundam who performs well with power slash and then can switch to double drain survivor later on, proving that survivor itself is a good move. Gabrielle is another example where it has plenty to do in the short term with slayerbreak, purifying mist and give turn then later (at a time bloodthirst would be charged) it can use drain survivor to start damaging any enemy rather than just ones with kills.
You might think of XYZ-999L or Aethereon being deserving of a time decrease on their double drain survivors, but honestly it’s just that they can do so little in the meantime which is the issue. Imagine XYZ had dreaded strike changed into a 50TU stun by +50s repeatable move that could only be used after cobalt coating, or Aethereon had assisted nova changed into a relevant support move. Then they’d be a much more cohesive and rewarding design.
I know that’s a lot, but I hope you can see where I’m coming from how the move itself has a good place in the game and 300s is a fine time to wait as long as the moveset of the monster is well designed.