Yes and it was common for the player to tune (and presumably retune) fixed-intonation instruments like the clavichord... Bach famously had his own tunings that

Yes and it was common for the player to tune (and presumably retune) fixed-intonation instruments like the clavichord... Bach famously had his own tunings that "sounded good". You still see this today with e.g. hurdy gurdy players who are constantly tweaking their tangents by ear.