At this level many routes are option routes based on the coverage look both pre and post snap, example two man combo against cover 2 may a chair concept where the QB reads the drop of the corner and goes short or hits the outside route in the hole. 2 man combo vs single high safety may be a be a seams concept if cover 3 and a crossing or over/under concept against man free.

It is the coaches responsibility to make sure they work these and correct during game week, as well as the receivers responsibility to watch film so they get comfortable.

I have to assume all of this is going on during the week and even if the defense switches things up, there are only so many coverages/disguises you can do during a game and this information should be coming down from the box so adjustments can be made on the sideline.