But honestly these gadgets ONLY get in the way of what you should be doing, putting hopeful negatives in the enlarger and giving them a try because you are taking "time" away from the darkroom, and the impression of whether or not a particular negative will make a good print is fleeting.
I'm finding that the opposite is true. The more time I spend proofing the better off my output is. Wasting darkroom time on inferior negatives is a problem. Often I will have an entire roll of a single portrait session. Which of the similar expressions is the one worth spending an hour printing? It's not economical to answer that question by spending 36 hours printing. Although I am sure that pro photographers with large budgets and assistants did just that.