Failed the initial practical after 6 hours of oral exam and several lesons taught. Everything had gone fine, including a question about weather reports. I'd been asked to name every weather report by memory, and the valid times of issuance for each. I responded that I didn't have it memorized, but would look it up. I began to reach for the reference, and was told don't bother, that's what the examiner wanted to hear.
After six hours, I was told to stop, and that I would be failed for not having known the weather info, several hours earlier. I was sent home. I returned a few weeks later on a new schedule, with the texts on weather at the time, all but memorized. I was asked if I had studied that material, and when said yes, the examiner said, "good, we don't need to talk about it. Let's go fly."
We spent an hour and a half in the air, half of which the examiner flew because he didn't get a chance t fly much. We spent a good share of the flight looking at fields, and discussing ag aviation, and agriculture in China (two surprising unrelated fields, by the way).
When we returned, I was issued the certificate. I was told that I would have passed the first time, but it was close to the end of the month, and the examiner had been under pressure to fail X percentage of his applicants. I was told that he needed to meet his stats, and I had been unlucky enough to be one he failed to meet those stats.
It's the only check or exam I've ever had an issue with, out of my career. The only failure, or difficulty. That examiner made his stats for the month, and I got a failure that stays with me for life. Fair trade, but typical FAA.