Soggy buns due to either failed to toast the inner side or having it sitting on the pass/heater for too long. Same applies to the meat side and the salad side achieving temperature equilibrium.

Too much height. If I have to disassemble the burger to put it in my mouth, it is not a burger anymore. It is just a mess then. Instead of two or three (or more!) patties stacked, try a bigger bun and an equally bigger patty. Or even a thinner bun to get the patty to bun ratio to what a triple patty burger would offer.