Sifnos is a Greek island that has an extensively upgrade and well-marked network of numbered trails due to a project starting in 2015. Sifnos has a website dedicated to documenting these trails:
https://sifnostrails.com/project/
>Sifnos Trails is a project of the municipality of Sifnos that started in 2015. In collaboration with Paths of Greece, the Municipality of Sifnos decided to improve the hiking trails network of the island. The old way-marks have been removed and new ones have been placed, thus harmonising the way-marking of the network. Sifnos now has more than 100km of professionally designed and way-marked trails, one of the largest trail networks of the Aegean.
I'm submitting Sifnos Trail 4 (not including the spur trail 4A goes to the village of Vathi) as it is one of the longest trails on the island and is self-contained loop. More information about this trail can be found here:
https://sifnostrails.com/portfolio-items/4-cedars-olive-trees-and-the-sea/
The trail is accessible via public transportation as the island's network of buses drops people off right at the trailhead from the main village of Apollonia, so it's a popular loop for tourists to complete.
