Think the most I’ve had were 13 drops and maybe a couple of collections. But does depend massively as you can only fit a limited number of pallets onto a 18T and some drops will be several pallets.
Skips - have seen some under a lot of pressure if they have loads of drop offs in a morning of the open top type. Saw one guys list and it made pallets look like a doddle.
RoRo skips will be less as its only one per location but you might be best off having ADR for that. Gives options for things like asbestos skips.
You could look at other options like waste bins used for medical waste. Think its SRCL who do that for example and its actually pretty easy. Basically just big wheelie bins.