Shyvana has fast clears because her pre-6 and even post 6 ganks aren't that good.
so why nerf her clears? that's just gonna make her shittier EVERYWHERE
the only way shyvana is ganking successfully pre-6 is if A: the laner she's ganking for hands it to her on a silver platter with good cc B: the enemy laner is severely overpushed with no wards
post 6 she has an easier time ganking, BUT STILL GENERALLY NEEDS PEOPLE TO BE OVERPUSHED IF YOU EXPECT HER TO DO ANYTHING.
her good jungle clears are the only thing even keeping her relevant.
and
just threw her over the edge because of how well they synergize with all AUTO ATTACKING JUNGLERS IN THE GAME.