Sled Training in Hypertrophy Phase

Ok, so im doing sled work with a homemade tire in my street. My street is pretty rough, and ive done up to 90lbs for shorter distances but this doesn’t allow me to do much volume.

Today I did my first official workout, and went with 70lbs. I did pulls and pushes lasting 20 seconds and did 8 sets.

My question is, during a hypertrophy phase, should i increase the volume by:

A) Adding sets - go from 8 sets all the way up to maybe 14 or 16

OR

B) Increase the duration of each pull, so instead of just 20 seconds, go up to maybe 30 or 40.

Lastly, would you recommend an even number of pushes and pulls, or do more pushes than pulls to hit the posterior chain harder?

Thank you.