I use basically one controller per element with some exceptions. Mini trees, live trees, and luminaries, which are programmed 3 channel string but I group these items left and right since they are on separate universes. Very intuitive.
LSP is really flexible. This year for my mega I went as far as 1 controller per strand and then created a mega tree layer and assigned the strands to it. I have a house outline layer and am planning an arch layer where each arch has it's own controller.
Manual calculation of the channels is the hardest aspect of setting LSP up but it really isn't bad at all after you get the hang of it. Once and done. If you don't have your elements built I suggest you leave plenty of room between channels for tweaking. Also, I find it very helpful to put the channels in the controller description. Screen shot of last years attached. I printed it and used it for programming my SSCs.