At some point I had issues with the above improved setup as well, because trucks waiting in queue blocked the road as well (when using low capacity vehicles especially, I use several for a line sometimes to get decent frequency, otherwise stuff goes on foot).
Nowdays I don’t set full load, it seems unnatural to me to be honest but I am not sure i that constant bouncing increases running cost (probably doesn’t) so in fact it shouldn’t matter whether you use full load or not (perhaps it’s not so easy to establish number of vehicles needed at a glance that’s all).