Doesn't "get better at retaining this information" have an inherent assumption of "in a certain amount of time"? If not, you could always just keep rereading the text until you memorize it.
Yes, but that's included in my point. Maybe the slow-reading with this font is less overall time than the number of rereads required in order to hit the same retention levels. It's also possible that reading something slower allows for greater mental association or memory building than just speed reading something 10 times.
There's a bunch of reasons why this could be either better or worse, depending on a myriad of different factors. I think it's a cool tool to have in your kit.
