Once, usually with a trailer on the back of the truck and cash in my pocket. If I like a horse I buy it, if I am wrong and we don't get on then I sell on.
Admittedly I am not paying 4 or 5 figures for a performance horse. It could be a different matter then.
Twice usually, but my last two I have bought from the yard where I was based so I rode them at least a couple of dozen times before I actually bought them
I tried mine twice. Did the whole caboodle both times, catching, tacking up, schooling, jumping, open field for a canter/gallop and hacking on road. Though I knew the first time he was the one I wanted! Was very lucky though as horsey friend who had spotted him and recommended him actually lived opposite him and had seen him being brought on over several months so I had a spy in the camp!