I personally LOVE Shen. He's one of the few Tanks/Bruisers you could even consider having a moderate skill-cap and he feels so satisfying to play. In that sense, Shen has a decently healthy jungle clear but is very, very slow at clearing said jungle. That being said, he also feels like a champ that would be a jungler if Riot would shift his kit just a little to make his clear faster.
Here are the changes I'd suggest:
If his Twilight Assault passes through a large/epic monster, give him 50% of the buff he normally gets, adjust the maximum monster damage to be higher and remove the current monster damage passive: Empowered attacks against monsters instead deal 100% bonus damage. That means if it passes through a large monster it'll give 25% increased attack speed and deal 10-40+(3.5/4/4.5/5/5.5+1.75 per 100 AP)% Target Max HP per hit.
Beyond that, the only other thing that would have to change would be his passive shield. I was always confused as to why the cooldown doesn't reduce on ability damage to large/epic monsters in general. The Ki-Barrier passive could also be reduced by 50% if need be making Ki Barrier's cooldown reduced by 2 − 3.75 (based on level) seconds if the ability activating Ki-Barrier hits a large/epic monster.
This is my idea for a better Shen Jungle. What do you think?