Clones as old as the muther, WTF. Yes till the new stem and leaves start. If that were the case I have 8 year old clones.
Perlite/vermiculite clones take about a week to come up with good roots. A air cloner about 3 days. Bubbler cloner about the same.
The groth of clones is a strain base , a ferts, air/ water, time elements.
IN the grow cycle of clones and grow sequence after the first week it a even groth rate.
Suggest you test your ph and air flow, also use antiwilt on the leaves, this helps the losses from the leaves.
Note the best groth is 18 hrs a day growing time. Plants need the change to dark, its part of there life cycle. After a couple hundred test its well proven.