I was wondering, what key challenges are considered the fastest/most optimal? Want to get into running this game but would like to know this before I start

The Fastest Missions

Genesis Era: The Buzz Bomber's Revenge(Classic Green Hill), Invincibility Challenge(Classic Chemical Plant), Balloon Bonanza(Modern Sky Sanctuary)

Dreamcast Era: Terror from the Deep (Modern Seaside Hill), Thunder Shield Challenge(Classic City Escape), Overdrift(Modern Speed HIghway)

Modern Era: Fire Shield Challenge(Classic Crisis City), Endless Boost(Modern Rooftop Run), Chase After Blaze(Classic Planet Wisp)

Thank you very much, next run I do i'll do these