ent_blend linear interpolates between two frames. Thus, the same as said before also applies to ent_blend.
The issue is simple math. All linear interpolation produces visible distortions when the follwing two conditions are fulfilled:
- the real movement is not linear, but a rotation or a movement along a curve.
- the frames are very different from each other, f.i. rotation steps of 30 degrees or more.
As a rule of thumb, the less linear the movement, the more key frames you'll need. This applies to bone as well as vertex animation.
