20–400 BPM, any time signature, five accent levels, subdivisions, swing, count-in, speed and gap trainers.
A triplet fits three even notes into one beat, counted “1-trip-let 2-trip-let”. Triplets are the backbone of 12/8 blues, shuffles and many ballads, and switching between straight eighths and triplets is one of the best timing exercises there is.
The metronome above clicks the beat at 70 BPM with three subdivisions in each, the in-between ones a little softer. Play three notes or strums for every click, then try switching to two (eighths) and four (sixteenths) without stopping.
A bar of 4/4 played in triplets has twelve even notes, the same as a bar of 12/8. That is why slow blues is often written in 12/8: the triplet pulse is the whole groove. Picking triplets, alternate strictly (down-up-down, up-down-up) so each beat starts with a different stroke, and keep the three notes exactly even. If the third note is late, slow the tempo down by 10 BPM.
“1-trip-let 2-trip-let 3-trip-let 4-trip-let”, with the number on the beat.
They train you to divide the beat evenly into three, the basis of shuffle and 12/8 feels, and moving between triplets and straight notes builds precise timing.