There is a particular problem in Los Gatos on summer weekends when everyone wants to escape the Bay Area and go to the beaches around Santa Cruz. Southbound Highway 17 comes to standstill due to idiot timid drivers who slow down going uphill and constantly brake around curves. Then the navigation apps route drivers onto residential streets to try and save a few minutes. It gets so bad that local residents are literally trapped and even emergency vehicles can't get through.

https://www.losgatosca.gov/2488/Beach-Traffic