This is only my theory and not yet fully proven but I have walked some of the trails with Phuket Hash House Harriers.
In the old days before there were roads on the island the monks from the Wats used to have pathways over the mountains to deliver important messages and escort travellers.Normally one leg was done per day.
For example:The primary Wat at Chalong has a path leading over the ridgeline down to the Wat at Karon.You can also stay on the high ground where the radar dome now is and reach Wat Patong.From Wat Patong you go over the high ground and by passing Kamala etc come down to the Wat at Chern Talay.
A lot of these paths are now in disrepair but still exist.Some were large enough for ox carts.Can you see them on Google?
