Efforts to automate this process already started:

actions needed for a long run (looping of 100 VMs migration) - using 1 ESX
need to merge it to a script - Creating a plan, running the plan, getting duration & cleanup
plan to test the script  with a small number of VMs (<=5) and running a few cycles

Following this effort we will increase total numbers depending on needs of available storage on target which is limited to 12 workers and uses ODF.