[hgsgm]

Classics is an extremely impractical format for ratings, because the games are so long so players can't play many games.

It's like Heisenberg Uncertainty.

[kzrdude]

Yet my impression is that the rapid list is volatile and often not reflecting the reality, the classical rating is better in tune with actual strength

[jstx1]

The number of games does influece the stability of the ratings but the result is the opposite - classical ratings are more reliable because there are regular organised events while there are very few serious blitz and rapid events. Most top players only play the rapid and blitz World Championship, no other events in these time controls.