Hi - if you're still having problems in Two Point Hospital make sure you've changed policy in the "Overview" screen - turn on "fast track treatment decision" and the people won't go to the GP twice. That should shorten your lines.
Also, train the people that work in the GP office with GP only. Often they can then fully diagnose someone without them having to go to any other diagnosis room. You can also turn the threshold down in this same screen. Hope this helps!