GigaBash

Story mode while skipping cutscenes takes roughly 50 minutes or less to complete. Not all levels have sub-objectives. If you're not sure how to perform a certain move, click Start, Options, and Controller. Many times the Paused menu will even show you the specific move for the sub-objective as well.

If you happen to miss a sub-objective, you can replay missions to mop up. I had missed some in the first story chapter, so I replayed from the start until I completed the sub-objective I missed. Achievement pops instantly once all have been completed at least once (across all playthroughs).