So, in general, they used much less pedal than pianists today.
But, when Classical-era pianists did use pedals as special effects, they often used them very liberally for large sections of music — even without changing the pedal.
So, in that sense, they used much more pedal than pianists today.
For example, by modern standards, the pedal markings in the opening bars of the third movement of the ‘Waldstein’ Sonata are very confusing. Beethoven instructs the player to lift the dampers for extended periods of time, even through dissonances. This was possible due to the fortepiano’s straight stringing and lightweight construction.
If pianists are not relying on the pedal, then the fingers must work much harder — using over-legato and finger pedaling techniques – to communicate the subtleties of musical expression.
Over-legato techniques hold notes under a slur so that they bleed into each other, maximizing the legato effect. For example, [scale playing] may sound perfectly legato by modern standards, but a deliberately over-held [scale playing] is a true legato by Classical standards.
In Alberti bass passages, one can use finger pedaling – holding down some or all of the notes – to create a richer harmonic support.
In this chromatic passage from Mozart’s Rondo in A minor, K. 511, most modern performers use the damper pedal with frequent changes to create a sustained effect. But, if finger pedaling is part of your expressive toolkit, then there is another sonic possibility. I play this entire section without raising the dampers. By deliberately holding down many of the notes, one can create an open, sustained sound while maintaining the transparency and clarity that are often lost with the damper pedal.
I encourage you to experiment with finger pedaling and over-legato techniques to see how far you can go before using the pedal. And, if you do use the pedal, see how much blurring you can achieve with half-pedal and flutter-pedal techniques for a result more closely aligned with Classical-era usage.