Add dirt. Make sure your gutters are sized right.

For looks and to reduce noise. You really shouldn’t have to work on a washer or dryer too often.

I have had better success with the stuff that has longer dry times. You just need to research the different brands. Sherwin Williams had a really good one, but it is not the same post pandemic.

Is the gap changing? Are the cabinets pulling away from the wall? If the gap is staying the same, get a more flexible caulk.