Connecting all 15 peaks over 3000 feet in Wales:  https://www.welsh3000s.co.uk/

Time is kept from the first summit to the last.

"The Welsh 3000s Challenge

In order to complete the Welsh 3000s Challenge you are required to have been at the top of all 15 of the mountains over 3000 ft in Wales within the space of 24 hours, without using any form of transport.

The length is about 24 miles, but the walks to the start point and down from the finish point can take it to over 30 miles in total.

This is a well marked route that passes through Kent, Surrey, north east Hampshire and into Sussex.  There is a race along the full (105km) length of the Serpent Trail each year since 2017, and course records are the supported FKTs for this trail.  See the race website.

Explore the heathlands of the South Downs by following the 64 mile long Serpent Trail.

A traverse of Los Padres National Forest from Cuyama/Ventucopa to Upper Oso Campground (outside of Santa Barbara). The route starts at the last gate at the entrance to the Dick Smith Wilderness on Forest Route 9N11. It follows this road until it turns into Buckhorn Road, which it follows until Buckhorn Road terminates at Upper Oso Campground, where there is a gate as the road turns into Camuesa Canyon Road. This is the path of least resistance, following a fire road with no major turns for the entire traverse.