> I don't use any skills, what kinds of skills are people finding most useful?

I create/edit/delete at least one skill per day. I can't imagine working effectively without those files.

The most common case: if I see something took AI too much time and tokens and it is done, I ask my Cursor immedietly after to save it as skill. So next time I do the same I just refer to skill. I don't need to remember the name of the skill, I just mention something like "do {explaining briefly the task}, you have done something similar in the past and it is saved as skill"