Operational trials question

[Kutscha]

On another board, a poster claimed the P-47M went through an ~3 month operational trials period before being cleared for operational combat status.

Now the P-47M had some problems when it arrived in England.

The question is: Is this just the interpretation of the poster because of the problems the P-47M had or was there really an operational trial?

I can see there being operational trials for new a/c types in theatre but this was just a change to a newer model of the same a/c. Usually these trials (afaik) were of limited penetration of enemy airspace but the P-47M, with questionable reliability, flew to Berlin. Doesn't sound logical to me.