I agree that generalized trees require too many clicks. What I really like are the limited depth, non-collapsing trees in a lot of UIs now. Like in Slack, wher

I agree that generalized trees require too many clicks. What I really like are the limited depth, non-collapsing trees in a lot of UIs now. Like in Slack, where the left nav has few top level nodes—pinned channels/chats, channels, and chats—that make it easy to get exactly what is needed. It’s not perfect (like I would prefer an aggregated pin that simply shows everything from all pins in one conversation dialog), but it is visually clean and efficient. And instead of a giant tree to enumerate all channels, you use a dedicated search interface that makes it easy to add entries to tree with a single click (without having to interact with the tree).