For active players it is more usefull to lock the boost instead of locking the creature.
I mean, you get a good boost as 40% of experience, experience or attack for shooters, so you use 1.59h of the boost, boost (instead of the 2 hours completly), and when it is about to end 'a few seconds left' you reroll the creatures.
This is what I do, as I got the 3 prey slots open, I usualy get some good creature to hunt. In the mind time I save all the reroll prey cards given by free from the daily reward, and when I got enough I select good creatures to hunt.