That’s all I ever do/did, 30sec with 2 min rest. I got up to 1 min sprint with 3 min rest but haven’t been on top of my HIIT game in a long time… did a set recently and 30 sec killed me. 😛
What I always do is this: Run for at least 30 seconds up to 2 minutes, then rest for 2 minutes up to 4 minutes, then do up to 8 sets or 30 minutes whichever comes first. To decide how long I should rest between sets I use this: If I can’t talk without gasping, rest longer. If I can hold a conversation then it’s high time to take off again.
Go by feel, as every body is different.