A quote from Leopold Auer where he was discussing how he expects his students to master technique.
"Art begins where technic ends" Violin Mastery Talks with Master Violinists and Teachers, Comprising Interviews with Ysaye, Kreisler, Elman, Auer, Thibaud, Heifetz, Hartmann, Maud Powell and Others By Frederick Herman Martens
He had assistants that would "prepare" his students with the proper technique before they could even have lessons with Auer.
This really seems true. If you are struggling with a technical passage in a piece and you don't really master the difficulties, it shows. You can tell when a violininst has conquered his technique and can just play and let the music flow.
This book is a fantastic read. We can all learn a lot from the greats. They are not all in here, but enough information is shared that would benefit any violinist.