It was over 15 years ago, but I was helping another CPA with his client's claim for Real Estate Professional(REP) status.

The taxpayer had over 20 rental properties, spent nearly every day working on them and driving back and forth, many over 100 miles away. He gave us a meticulous spreadsheet with days and miles, for every day, including Xmas and NY's. (!) Really?! Much, much more than 750 hours in a calendar year.

Many, many hours. He even had a full time job besides the rentals. 

The agent threw out many of those so-called working days, but still had much more than 750 hours; however, there is also the more than 50% test, too. With a full time job besides, the 50% tax would have been problematic.

Fortunately, he only worked 4 days a week for part of the year, and then he was work-disabled for another part of the year(only disabled enough to not be required nor allowed to work at the job), so that brought the total hours worked down and the REP hours up above the >50% test.

The agent flunked him anyway, and that's the last I heard about it.

ps I loved IRC Section 469. Made a career out of it. I could have written a manual about it and taught about it. (Oh, wait, I did!)