I remember my first piano teacher had an interesting technique to help at difficult parts of a piece.
Instead of playing the actual rhythm, I would pretend it was (kind of) dotted 8th notes alternating with 16th notes. Then, I would do the same thing, but starting with a 16th note, alternating with dotted 8th notes.
I would do this only with separated hands and always ff. It was very useful because it helped muscle-memorize every note transition.
Is this a known technique??
It is indeed a known technique. Very, even.
Cortot was a famous proponent of it. You can find copious examples in his pedagogical editions. You can also find examples of famous pedagogues who disagreed with it. If memory serves, Neuhaus was lukewarm toward the method in his book.
I know of no universally accepted name for it. My teachers simply called it practising in rhythms.
Examples
In response to a comment asking for examples of this method of practice, I have added some excerpts from Cortot's edition of Chopin.
From the étude op. 25 no. 2,
the suggested variants:
Comments from the end of the fourth Scherzo including suggested rhythmic variations:
He writes that the rhythmic variations throw the accent away from the beat, developing the independence of the fingers.
