Yes, following on fron sucom's comments I remember that Chopin said that to speed up scale playing (not quite what's under discussion), you must increase your speed gradually. Obvious - but no one thinks of it. The metronome gives a method for holding back speed until the necessary stamina and coordinations develop.
Yes, I totally agree with this. Too often it is believed that pushing the speed, even if control is lost, is the key to increasing speed, and certainly there are times when pushing yourself will help improve speed (and a feel for the flow of the music)
in general. However, if specifically trying to speed up a certain passage, or piece, it is really important to increase speed
while at the same time maintaining control over expression, fingering, evenness, etc. Gradually increasing speed, whil
e maintaining control, is really helpful and, in my view, very important.
I have discovered, after many years of practice, that if speed is always given priority over speed
plus control, a section of notes can remain uneven for years until control is exercised at the same time as attempting to increase speed.