The downpour in Salzburg came near the end of our guide's intro walking tour. The dozen or so of us took shelter together. When it started to let up the others headed quickly to their planned dinners nearby. I stayed with the guide and we waited it out for another 15-20 minutes and chatted with other folks till it ended. The next day was sunny.
In the Alpi di Suisi, the day started out magnificently, with nearly full sunshine. I was on a lift by 9 am and had lots of time to hike, look at wildflowers and stop for a hot drink at an inn. I was on my way down to the lifts about 4 hours later when the downpour came and lasted well over an hour. I managed to take refuge in a hotel and warm up/dry out with some hot chocolate. About half the group ended their visit when the rains came. The rest, serious hikers, took shelter as best they could, waited it out, and had dry somewhat sunny conditions to finish their planned hikes. Most of us had dinner that evening at outdoor seating to enjoy the view and sunset.
We had only 2N in Lauterbrunnen. A year later RS changed the itinerary and added 1N. Because there was no point in going to the peaks, we all hiked in the valley and/or in Murren and Gimmelwald. At least there was no rain.
Chamonix was off and on sunny. There were hours with great visibility on Aiguille de Midi, though it was clouded in some of the time.
You just never know what the Alpine weather will bring.