If you want to ignore Exchange stalling on your moverequest slow source/destination servers:
Get-MailboxDatabase „ex2013-db01“ | Get-Mailbox | select -first 5 | New-MoveRequest -TargetDatabase ex2016-db01 -BatchName gna -Priority Highest
Monitor with:
get-moverequest | get-moverequeststatistics
When they’re all Completed, cleanup
get-moverequest | remove-moverequest
Then repeat from step 1.