Could "engineering works" be used to expediate new fleet rollouts?

[brad465]

Seeing how shambolic the 701 rollout has been and still is, I wondered if what SWR needed was a large block of time (such as 1-2 weeks in a school holiday), where something like half of their services are suspended, but the railway physically remains open and the drivers and other staff freed up are solely dedicated to rolling out a new fleet? I think this could speed up training and identification of problems through increased capacity to do test runs. If this was enough to get a critical number of units into operation early on, this could facilitate a faster rollout later on from a strong foundation without having to temporarily cut passenger services further.

SWR is the main example I can think of, but other operators with potential large-scale fleet replacements coming up include Northern and Southeastern, could such a strategy work for them?

 

[signed]

People will still need to travel on school holidays and a mediocre service is better than no service at all

 

[LittleRedTrain]

ISTR SWT did something similar when training up drivers for the Class 450s, or may have been the 456s.
Quieter routes such as Ascot-Guildford were bustituted to free up staff for crew training.