What's the most foolproof approach to sight-reading treble clef without impacting my (already spotty) bass clef knowledge? Is it OK to "compartmentalize" the two clefs to different parts of the fingerboard, as I describe in a) below? It seems whenever I work on treble clef sight-reading, my bass clef skills suffer, especially in Simandl 4th position and the transition area. Background: I've only been reading music (bass clef) for about 6 years, and I'm still a bit spotty at it up in the ledger lines. I've been trying to improve (bass clef) sightreading up around the heel (Simandl 4th position), but I've ALSO been trying to learn to sightread treble clef, because 99% of lead sheets I'm looking at are in treble clef, and I want to be able to grab those melodies faster. Treble clef sight-reading seems more valuable to me right now than reading bass clef ledger lines. Strategy: I have the best luck with sight-reading when I treat the instrument like a horn or the piano, i.e. there's only ONE SPOT on the neck to find each note. So I'm thinking I should always default to thumb position when practicing treble clef sightreading? a) Should I ALWAYS switch to thumb position for treble clef? (Just to avoid confusion). So the 10th "fret" C on the D string is reserved for BASS CLEF (first ledger line ABOVE the bass clef), and 15th "fret" C on the A string is first ledger line BELOW the treble clef? (Yes, I know they're the same pitch.) b) Or should I be able to read both treble and bass clef in Simandl 4th position (at the neck heel). I feel like long term, this is where I need to be, but whenever I drill one clef, the other clef suffers. My aging brain can't keep them apart. c) Or should I damn the torpedoes and treat middle c (first ledger line below treble clef) as 3rd "fret" C on the A string? (transpose everything down an octave) Has anyone successfully conquered this issue as a late-in-life sight-reader?