Revit automatically warns me when lines are not going to be joined in a sketch (think model in place item sketch) or drafting view. Not needed - it kills efficiency - there should be an option to turn it off.
We can write a small add-in that catches the notification event about the impossibility of connecting lines in the sketch, and neutralize its notifications. Thus, no warning will pop up for the end user, it will not distract the user and slow down the design process.