For folks using iD and JOSM, having a bunch of relations in the editing area can make things quite frustrating to edit.

I totally hear you about selecting can be a bother. iD has '\' as a hotkey for "select the next way that shares this node" and JOSM has the rather cumbersome "middle click to cycle through coincident objects". It's also not helped by iD trying pretty hard to hide that relations are a thing or JOSM pulling all relation selection/editing into it's own side interface. And don't get me started on relations of relations ha.

I'll have to fire up Merkaartor sometime, differences in editors definitely can make "best practice" more difficult.