First swarm calls of spring in Mendoza — bait hive box size, height, and how often to refresh lemongrass oil?

Spring in Mendoza has arrived hard — the almonds are done, the plums and peaches are out, the poplars are pushing pollen, and the phone started ringing this week: three swarm calls in four days, two in the same barrio. Twelve colonies of my own and I'm managing them for swarming already, but the free bees are the fun part. I'm putting bait hives out this week and want to tune them. Right now I use a full Langstroth deep, ten frames, one old dark brood comb, the rest foundationless with starter strips, a few drops of lemongrass oil on a cotton ball in a small bag, entrance reduced to a slot. Placed about 2 m up on fence posts facing north-east, in shade after midday. Questions for the swarm-catchers. Does a full deep (around 40 litres) catch better than a five-frame nuc for you, or is that just Seeley's number being repeated? How high is worth the ladder? And how often do you refresh the lemongrass — I read it fades in a week and I read it lasts a month.