Could always do more then 1 dungeon/primal while your on lockout...

Some people are always gonna burn out when they fixate on a single instance over and over. Personally i'm fine with lockout periods.

If i had a deciding vote i'd go with a 4-6 hour lockout with a fairly good (25%-ish) drop rate, with a 100% totem/dungeon mark drop rate. Combine tangible progress Totem type mechanic, with better drop rate for a 4 hour lockout. You could do about 4-8 different dungeons/primals by the time your first runs timer is up.