I went from 40-45wpm on Qwerty to 65-75wpm on Dvorak, but after I stopped practicing, I settled somewhere in the high 50s low 60s. I specifically measured because I wanted to be able to quantify the changes. Speed wasn’t my only concern, but it’s the biggest change. There’s no need to learn an alternative layout, but even people who don’t may benefit from a small adjustment like making caps lock a left backspace and learning to touch type. In retrospect, I would consider more of the alternative layouts before jumping to Dvorak, but I don’t regret it at all, even at work or with games.