Orchestral Music: How well synchronised in time do musicians have to be to sound as if they are playing together?
07.06.2025 06:07

Perfectly, in the ordained time.
I remember, also, a single Violin holding an E6 far longer than notated in the finale to Wagner's Overture to “Tannhauser”. As the Violin figures in this Overture are among the best ever written, I found forgiveness in my Musical heart.
Aside: Wagner FOREVER!
While emptying a house, have you ever seen something in it that blew your mind?
I recall a single English Horn entering a millisecond before their due admittance at the outset in a recording of Wagner's “Ride of the Valkyries”. Not only this, but his/her assigned tremelo was to be from C#—D Natural, (Concert F#- G natural before transposition). The performer instead quavered between a C#—D#, (Concert tones F#—G# before transposition). The errant reading by the Hornist was impermissible and the recording should have been halted and begun anew. Yet, it was not. Worst recording ever.
Pay attention to what's written and placed before you, fellow Musicians. It’s YOUR/OUR JOBS!! (Unless your part/passage is demarked as ad-libitum..”at you liberty’ or a piacere—”at your pleasure”, submit to the notes written and their proper duration in hold!).