What is the difference in between the different STFT implementations? (Overlap-shift with zero-padding, overlap-add, overlap-save, etc)
Compressing the time axis of the overlapped windows into the original duration is one way to make a smoother spectrograph image.

Also, bell-shaped windows are lossy near the edges (after re-quantization), but a 50% overlap of Von Hann windows recovers all that information in each overlap.