While retuning motions and/or drifts in strict JI renditions are one or more commas in magnitude, adaptive tuning reduces these to fractions of a comma by spreading the motion among all the chord changes in a progression.
The desideratum, at least in more modern times (making use of the computer) is usually to allow dynamic alterations of the pitches during the performance of the music.
Various approaches have been tried, one of the earliest examples being by Nicola Vicentino in the 1500s. In 1999, John deLaubenfels and Paul Erlich were very active in developing a good adaptive tuning algorithm.