Education has become "initiative mad", leaving no time to reflect, plan and consolidate, Richard Goring, the union's education convener, said.
Under Higher Still departments would have to cope with new and administratively onerous assessments, exacerbated by problems of accountability and internal and external moderation.
"At the same time, there will be, for many, preparation of courses at other levels - Intermediate 2 and Advanced Higher - for the following year. Many of these are new courses, with new content and new assessment techniques and requirements. Subject departments such as English and business studies will have this two-year workload crammed into one."
Administration at departmental and school level would increase with pupils being enrolled for every unit, course award and group award.