InnoDB uses MVCC, so the only operations that respect the SELECT .. FOR UPDATE queries are updates. As long as you use transactions, I wouldn't say this is a common application pattern.

It was good for the article to mention gap locking/next key locking - a lot of users are surprised by it. The only comment I would make, is that it not required when using Row-based-replication: http://www.tocker.ca/2013/09/04/row-based-replication.html

I also have a 35min video as well which describes locking: http://www.tocker.ca/2013/09/19/locking-and-concurrency-cont...