Hello, 
Currently when pressing a skill on hot bar it will typically have to be mashed depending on the preceding skill. This can cause a gap between the two skills that would not normally be there if you were to hold/buffer the subsequent skill keybind. The gap is small (milliseconds) depending on how fast you activate the input or preceding skill, but if both skills are protected the gap can get you cc'd, miss a combo etc. The most common example is keybinding rabam skills. The inputs are not preferable for some players and one rabam cannot be buffered at all. 

Currently the only way to get around this is to use keyboard software or macros to rebind the key which is technically against ToS. 

TLDR: Allow a hotbar skill when hold to flow from the preceding skill. At the very least for rabams.