The all-fourths tuning, also known as the P4 tuning, is a regular tuning that has a measure of popularity among electric guitar players in particular.
Because it is a regular tuning, the interval between every pair of successive open strings is equal (a perfect fourth). As a consequence, there is perfect pattern regularity across the fretboard. This eliminates the need for alternative systems like the CAGED system, which belongs to the domain of standard tuning.
Players associated with the P4 tuning
Tom Quayle
Tom Quayle is a jazz-rock virtuoso well known from YouTube and a prominent advocate of the all-fourths tuning.
Stanley Jordan
Stanley Jordan is known for his two-handed tapping, which the regular fourths layout supports particularly well.
Allan Holdsworth
Jazz-rock patriarch Allan Holdsworth also made extensive use of this tuning, particularly in his SynthAxe days, when he could switch tunings at the press of a button.