Jumping directly to labels is a bit complex. Essentially, you need an extracted version of the game so that the .rpy files are available (not .rpyc or .rpa). Then, if you know the label you want to jump to, you can just open up the Ren'Py console and type say
jump b_room
(#not an actual label in JD probably, just putting this here as an example)
or whatever the label is, and attempt to play the scene through. The rub here is that you need to know the hour, sometimes the day comes into play, and often there are variables that change the progression of the scene.
So the time you spend researching the scenes and variables by scanning all of the different .rpy files is time consuming, but if you see artwork in the /images folder that you haven't seen ingame yourself, and can't figure out what trigger you missed along the way, yeah...
Some might argue that after just grinding a lot more you might finally figure out the trigger, but some of us have lives...
Hopefully that answers your question. Most people won't do this, but since I'm familiar with Ren'Py, yeah for me this is just faster sometimes...