Your concern is definitely a real important one. If your egr cooler is compromised in any way, then don't delay in getting it deleted or replaced. The longer you let it go, the greater the chance that collateral damage may occur. The egr cooler usually fails due to a clogging oil cooler. Egr cooler failure can also lead to head gasket failure or hydro-locking of the rt-bank cylinders. Letting the motor idle less is not going to ensure much.
Its not being driven right now, parked it once i found out and would like to fix all the common problems at once when I am in there, I would reall like to give it a good flush before all the work starts, and understand it needs motor heat to assist in using the restore flushing products, but yes dont want to run the motor any longer than needed, In that write up they say to let it high idle or drive for an hr. etc.