The way I operate is to enter the call sign to get a beam heading, but that also sets the Start Time. I typically click on Worked Before (or something else) and the QSO Start Time gets locked while the End Time increments.
I may not work the station for 20 - 30 minutes or more.
While LoTW has a +/- 30 minute window, unless something change ClubLog's window is 15 min +/-.
Sometimes I forget to fix the time

Cheers,
GS K5GS