Only once; I had a punt that I enjoyed but for some reason didn't unload and left blueballed. Reasoning I still had the afternoon to myself, I made a quick appointment with a trusty "plan B" massage provider, who no doubt though she must have done a great job when I released with hair-trigger sensitivity!
In hindsight it was self-indulgent as sin and a costly way to get your rocks off, but hell, you only live once.
I've done the same a few times
The first when couldnt get it over the line

& the second third WSWS when it turns out the massage burd didnt

A game of two halves inexplicably not being able to shoot
The 1st half its a struggle
& the 2nd half chocks away
I wasnt quite hair trigger but not far off
Had to give notice to the 2nd massage burd to ease things down, far earlier than i would otherwise do
As a distraction i had a think about the different knob handling techniques each of them employed
When it was thunderbirds it felt more intense than usual
I dont think its indulgent paying for another pair of hands to finally get the tanks emptied
I regard it as a wise investment
To put things into context massage only stuff so not significant spends
& on both of the WSWS burds my doubts were increasing on arrival so i scaled the sessions back from 60 to 30 mins
Putting this down to communcation confusion