Or search: irregularity, unregularity, intermittence
3 Syllables: SUU
Brittany, differently, distantly, litany
4 Syllables: USUU
consistency, consistently, deficiency, efficiency, efficiently, epitome, exigency, indifferently, indignantly, insistently, persistency, persistently, polygamy, proficiency, sufficiency, sufficiently
5 Syllables: UUSUU
inconsistency, inefficiency, insufficiency, insufficiently, intermittently

Found 25 words across 3 groupings.