Always as little as possible except for peaces that are supposed to be 'rich' in tone?
In a simplistic way, it's a 'legato' pedal. With Bach some people avoid it, and I'd say that one reason is that he didn't play on the pianoforte, and consequently didn't have such a pedal. With Mozart it's a bit more complex, because this pedal existed by then, but he seems to only have ever made one brief comment about it. Beethoven was a genuine
legato player, and used the pedal. One famous example is his request that the pedal must be pressed
and never lifted during the Moonlight sonata, first movement. There's also the 'recitative' section of the Tempest, first mvt, which
must be pedalled as Beethoven wants it (never lifted), otherwise it looses its dramatic impact.
With the romantic composers, the pedal becomes a tool of creativity. There's many original pedal marks by Schumann and Chopin to show how they used it for many more effects than just legato. If you play Chopin's own markings, you'll see how he uses it to create rhythms and colours.
The modern grand, which was virtually 'finished' appr 1860 or so, is capable of such sustain, power and clarity, that the use of the pedal has had to change. Today we normally pedal as 'cleanly' as possible, avoiding clashes between, say, consecutive chords that are disharmonius. Following Beethoven's or Chopin's pedal marks today can make us slightly confused. They pedalled
differently in the first half of the 19th century, but their instruments were different too.
Still, today we can also use it creatively, as a subtle tool of colouration. Horowitz is an obvious example to learn from.
There are many examples of how one can use it. As soon as I think of any, I'll post
