You must remove all +1/+1 counters from Sage of Hours to activate its ability, even if the number of counters isn't a multiple of five. For example, if you remove twelve counters to activate the ability, you'll take two extra turns. If you remove three counters, you won't take any extra turns.

Heroic abilities will resolve before the spell that caused them to trigger.

Heroic abilities will trigger only once per spell, even if that spell targets the creature with the heroic ability multiple times.

Heroic abilities won't trigger when a copy of a spell is created on the stack or when a spell's targets are changed to include a creature with a heroic ability.