Why practise technique in isolation? There isn't really any gain. My teacher always talks of how someone should publish a compendium of technically difficult passages from the core piano repertoire, divided into sections by the technical demands it poses. For example, the section on octaves would have the octave passages from the Tchaikovsky Concerto and Brahms 1, and from the Liszt Sonata, and the Glissando section could have the awful 3rds glissandi from Alborada and the octave glissandi from Waldstein... Anyway - you get the gist. Why don't you select an area that you want to work on, and start working on passages from important works - even if you don't intend on learning those works just yet. Ultimately, when you do come to learn those works, it will only make them much more manageable if you can already play those passages, no?