Wondering if the OP runs camera/s; may be worth thinking about. These days I run a forward Go-Pro + powerbank, & long running ebay-special cam to the rear. Oncoming drivers slowing up/not on narrow sections, is a continual issue. On one occasion (narrow lane, no camera) small flatbed bombing along towards us, we had to cycle into verge. As they went past, I stuck my arm out and shouted slow down. They slammed on anchors, got out, and had a swaery gammon fit. Fortunately they were a way further on, when we just set off. No time to slow down for a few seconds, but enough time to stop be a total 'carrot'. Most common bad manoeuvre I see are poor overtakes by drivers who narrowly avoid a collision with oncoming vehicle - which may or not have to slow considerably to avoid.