Does Random.Range support variable speed over time?

i have animations that play randomly, all is ok unitl i try to speed up the animations over time. The animations just stay at same speed. Without the random.range animations are affected by time, but the animations just play in sequence order. Any ideas?
many thanks:)

OK thank you very much for your reply. Animations are legacy. “spin” & “Roll”.what iam trying to do is fairly straight forward. Animations are currently randomly playing fine with random.range. now As I am calling on a timer script I wish for the animations to speed up over time. At the moment I have an if statement saying less than 30secs make speed = 2; to be twice as fast.that works OK. But a second if statement saying greater than 60secs speed = 4 it fails to recognise. All this is in an update function. I hope this clear. I can paste my script if it helps? Thanku