As I said. Its a last resort to deal with knockbacks (after you exhausted arms length). And even then, you should know pretty quickly when those knockbacks come and use gauge for that then. Not just permanently sit on gauge the entire fight. I'm not saying you will never need to reposition via onslaught, only that fights are scripted so holding resources "just in case" isnt optimal play because you should never be surprised by things like scripted knockbacks. Similarly holding gauge because you "might less up arms length" is just you playing poorly when attacks are scripted. Do you also hold onto holmgang "just in case" you fat finger vengence before the tank buster? Of course not. Holding resources just in case things go wrong is always the least optimal play. Its sacrificing resources because you didnt plan in a scripted fight. Sure you 'can' play that way, and in lower content it wont even matter. But if you are progressing in raids, you need to suck it up and learn the fight script and plan your tools around the fight. Not sit on your kit 'just in case' you screw up.