The easiest way to ruin a wedding morning is to let the hair and makeup schedule run twenty minutes late. It creates a massive domino effect that completely destroys your portrait time.
I always put a hard stop time in the morning spreadsheet. I tell the makeup artists that everyone must be completely finished one full hour before we actually have to leave the hotel room. You need that hour to put the heavy dress on, find your shoes, use the bathroom, and let your mother cry. Putting a wedding dress on is not like putting on a normal dress. It takes a solid fifteen minutes just to deal with the buttons.
When my sister got married, her hair stylist spent forty five minutes trying to fix a single bridesmaid’s complicated updo. My sister ended up rushing into her dress and we had exactly four minutes to take pictures in the hotel lobby before the shuttle bus left.
Build a massive time buffer into the getting ready schedule. If you think hair will take three hours, schedule four. Sitting around in a messy hotel room drinking lukewarm coffee is much better than yelling at your bridesmaids to find their earrings while the photographer waits downstairs.