When I need landings we just call up the front office and they FBO (buy the trip) from the FO and block it from lineholders taking it. Hence, the reserves being "assigned" a trip more than a few days in advance.
The other option, which I'm a bigger fan of, is to go nonqual on landings, then go to DEN during my reserve days to do a landings class. Just like this month. I've done one LHR 3 day and then I go to DEN to get my 3 landings in. It's much better to bid reserve and dodge work versus being a lineholder and not be able to trade trips around.