Keytlebell coach

Coach is adding time not weight as i progress. For example i have always rowed at 20kg 10 or 12 reps for 3 rounds. Coach is asking me to do 6 rounds of 50seconds each side at 16kg. Should i 1)
stick with this and take breaks when i need to
2) reduce weight as i hit exhaustion but stick to time
3) stick with my original weight of 20kg but ignore coach time and just do 10-12 reps for 6 rounds?

Not sure which will make me progress faster.

50 seconds equals about 22 rrps per side for 6 rounds. This is a lot for anybody right? Not clear what the goal is. Feel like i’m being steered to a low weight high rep training which is not what i need