If you are making a lot of similar compounds in a series, and you have UV activity, it is pretty easy to set up a method that will let you inject a compound and run a column in a few minutes with full automation, collecting only the UV peaks. In many cases, (other than free labor from graduate students) this will allow you to make and purify 2 to 3 times more compounds a day if the chemistry is simple. I have made and purified 10 compounds a day when I have small, simple reactions to run in parallel.
If you are doing large scale, preparative work, or have no UV activity, they are less useful, unless you either spend a lot and get ELSD or MS detector, which adds a lot of cost and complexity. Great for big pharms, harder to justify in universities. But I think they can make most chemists more productive, especially if they know how to use them well.