At the GPs is it best to raise every health concern you have, or to just stick to the one reason you gave in the booking?

At my GP I'm told to put only one thing in the form to book appointments, and the meeting is generally guided to be as perfuctory as possible. But tomorrow I'm heading to a walk-in. There's honestly so much wrong with me and I don't think they're touching the surface in the usual appointments, so if i can just kill several birds with one stone it would be nice.