I have a little portable steamer that I use all of the time. It’s become one of those tools in my arsenal, along with my scale, that I had no idea when I bought it how much I would use it.
I use it the most when I’m sampling. I’m not a patient spinner and I want to see what my yarn and knitted swatches are going to look like as soon as possible. Steaming is perfect for that. My steamer is small and is best for small skeins of yarn. I used to just hold my skeins over our electric kettle until I got tired of finding wool in my tea.
I have used it for bigger 400 yard skeins, it took a couple of passes with my little steamer, but it was less time than waiting for the skein to dry after wet blocking. All I want to do was get started knitting!
I do need to say that if I am working with a fiber or blend that is new to me I will take the time to wet block my sample yarn.
A steamer is great for blocking swatches too. I pin them out first and then hit them with steam. I also use it to do touch up blocking on knitted or woven garments or accessories that are looking limp. A hit of steam can get a cable to stand back up, or get a quickly pinned out lace edge to open up.