No it isn't. Some bosses can lock before you can even get a handful of autos off. Besides, what's an extra ~100 poison damage when resisted and fluctuated in such a short time frame? compare that to the possible multiple 2-3k hits from riposte.Even if you are dagger still use double attack.
Dont use riposte as a locker. You are much better off using poison weapons. Its also useful when you level so helps both. Whilst riposte is mor useful for leveling, overall poison weapons is more benefitial when applying to boss and lock.
The riposte poison weaps is my personal opinion as well as from experience
Riposte is good for bossing where you can get aggro.