Trip axle question

In my experience I usually do just one side of the trailer (2 chocks between the 3 axles). Otherwise the axles just seem to push out of the way and I have had it move before with them on opposite sides. Most of the time I have one side or the other sitting on leveling blocks and I do that side to ensure it won't start rolling off the blocks. I also make sure it can't roll downhill on all tires touching the dirt (the desert is never truly flat). Sort of added insurance but I'm paranoid ever since I watched it slide 6 inches about 5 minutes after unhooking the truck. Thankfully the front jack was on an 18" long 2x10.