Originally, the Slayers were intended to respawn every 50 minutes (like the named), and the named to respawn every season (which from what i've heard slayers should do too but a bug make them respawn only at server reboot).
By the time the bug could be resolved and slayers / named spawn swapped, too much time had passed so they stayed with the current model
By the time the bug could be resolved and slayers / named spawn swapped, too much time had passed so they stayed with the current model