Not a good idea to waitlist in the higher classes when "A" or "D" is sold out and you're waitlisted in A, F and D and J at the same time. Because the airlines will probably try to clear the higher classes before the OW booking class. Leave it in the lower booking class.

The airlines can actually refuse giving you the seat when they realise that you're double or triple booked. You're basically denying someone else who needs that seat.