Play to Out Point...then stop.

You've selected an In (I) and Out (O) point for the current Timeline and want to see how the piece feels when it stops at your Out point. Easy, just place the playhead before the Out point and hit Shift + P for "Play to Out". It's kinda like clotheslining the playhead.

This will play from the current frame to the Out Point.

It's different than Shift + \ which is Play In to Out and only plays what is marked between (and including) the In and Out points of a timeline or clip.

I find Shift + P to be really helpful in judging when a clip should end especially if I'm breaking up long edits into smaller more digestible chunks.