Yes, you should always use the same vocal technique, whether you sing solo or in a group. However, choral directors sometimes want you to modify your tone (change the way you sing) in order to blend with the other singers in the group. This may be okay for those singers who have developed a solid vocal technique, but dangerous for those – the majority – who haven’t. You blend, all right – but at what cost? A singer should never compromise correct speech-level technique.