when you play with too much players in mid this means that you want to demonstrate the mid and the possession so make you attack through the mid would be great ... because this formation has only one strong point (too much MCs means attack through the mid)
and about the whole pitch, yes you must use the whole pitch if you will attack and vice verse if you will defend ... it is clear m8.
And after this I want to say that this formation may work great with your current main squad and may not ... so always try to change the formation to get the suitable one for your team.