Shen's ult could scale arrival time rather than HP
Basically, Shen arrives faster if he ults a low HP ally, and arrives slowly when used on a full HP ally. Possibly adjusting even as the target takes damage.
Currently, Riot is looking at nerfing the shield value and scaling it on missing HP. But this won't curtail his ult offensively because he's going to a location for his cc/damage anyway. Instead, this change would slow his arrival when used offensively and allow Shens better chances of making savior plays.
Notably, countering his ult by ccing him is also affected by this change.