It's all about how you use it
I issue a dose when I put halter on, another when they are tied for grooming and tacking up then again before mounting or leaving the yard/loading. If they 'activate' a top-up is needed some are good to go after three doses others need regular topping up.
If they go 'right off the deep end' you've lost the battle and another remedy maybe required like spook buster.
I've really found it useful for napping behaviour that makes it frustrating to maintain focus when working - ie they're checking out what their friends are doing instead of listening and tuning in. Also when they need to travel on their own and find it hard to load since it means going out alone.
The remedies help them cope and stay within threshold - but it's not a sedative or a miracle cure that transform your firebreathing dragon into a pusscat!