Ask a musician how much of their last practice session went to playing pieces they already knew, and how much went to reading music they had never seen. Most can not answer. The proportion has never been a conscious choice — it just happens, and the default almost always tilts heavily toward the familiar.
Repertoire practice and sight-reading practice use the same instrument and the same hands, but they make fundamentally different demands on the brain. Understanding that difference is the first step toward using your practice time more deliberately.
Most Practice Time Goes to the Known
The bias toward familiar repertoire is not laziness — it is human. Running through a piece you have already learned feels productive. There is flow, there is satisfaction, and the result sounds reasonably good. Reading a new passage you have never seen feels slow and error-prone. The feedback is unpleasant.
Over time, the path of least resistance dominates. Practice sessions become mostly confirmation that you can already play what you can already play. Skill develops only at the edges of comfort, and the familiar repertoire run-through has moved well inside that zone.
Why the Two Types Use the Brain Differently
When you play a memorized piece, the brain is tracing a path that already exists. The neural connections have been reinforced by prior repetition. Attention is still required, especially for refinement and expression, but the underlying pattern is established. Cognitive load is lower.
Sight-reading is structurally different. Encountering a passage for the first time forces the brain to process a pattern it has not encoded before. The visual cortex, the auditory cortex, and the motor cortex are all recruited simultaneously, each working without the benefit of an established shortcut. Processing is serial at first — identify the symbol, retrieve the pitch, find the key — and that seriality is what makes sight-reading feel so demanding.
The fatigue is meaningful. It signals that new connections are being built, not old ones reinforced.
What Sloboda's Research Shows
John Sloboda and colleagues analyzed the practice habits of 257 music students across different achievement levels in a landmark 1996 study published in the British Journal of Psychology. Students kept detailed practice diaries and categorized their activities. The results showed that higher-achieving students not only practiced more overall, but practiced differently. They spent proportionally more time on what the researchers classified as "formal" practice — structured work with clear technical goals — and less time on casual, informal play-through of familiar pieces. Exploring new music, which includes sight-reading, was a consistent feature of the formal practice category (Sloboda, Davidson, Howe & Moore, 1996).
The implication is not just that more practice is better, but that the composition of practice matters. An hour divided between challenging new material and comfortable repertoire tends to build more skill than an hour spent almost entirely on what you already know.
Self-Regulated Learners Practice Differently
Siw Nielsen examined the practice strategies of music conservatory students, publishing findings in 2001 in Psychology of Music. The students who showed the most consistent development shared a pattern: they deliberately varied the type of practice across sessions. If one session had concentrated on polishing a specific piece, the next would include a meaningful block of sight-reading or technical work on unfamiliar material. They treated their own practice as something to be designed rather than just done.
Sight-reading served a dual function in these students' practice. First, it directly trained the reading skill. Second, it acted as a diagnostic — passages where the reading kept breaking down pointed directly to the gaps that needed attention in other areas of practice as well (Nielsen, 2001).
A Practical Time Split
For a thirty-minute practice session, a reasonable starting structure looks like this.
Repertoire work (20 minutes): Focus on a difficult passage in the current piece rather than playing start to finish. Isolate, repeat, refine. The goal is technical precision and musicality within known material.
Sight-reading (10 minutes): Take a short passage you have never seen before and read through it without stopping. When one passage ends, move to the next. Do not linger and polish — the point is continuous processing of unfamiliar notation, not a clean performance of any single excerpt.
As total practice time grows, keeping sight-reading at roughly twenty to thirty percent of the session maintains a productive ratio. The discomfort of sight-reading is a reliable indicator that it is being done correctly. If it always feels easy, the material is too familiar.
The two types of practice are not in competition. Repertoire practice deepens your command of what you can already read. Sight-reading expands what you can read at all. Widen the range, and everything in the current repertoire becomes easier to learn the next time.