Is it better to take sectional mocks or full length mocks from cracku??

Sectionals.Try attempting CAT 2017,18 both shift papers as full length mocks.That will help you a lot.

Our mocks from DashCAT 16-20 are very good and are very close to the actual CAT paper. We are also uploading video solutions for the important questions for these mocks. Do give them a try.