While I think most say it's not essential for snakes (as it is for some other animals) & I personally don't use them, I'll also say that over the years of keeping snakes I've always had a sense that the occasional outdoor sun exposure has beneficial effects on a snake's metabolism & appetite. (caution: NOT in a container & NOT if temperatures are too high)
So whether you want to try adding the UVB light* or actual sun exposure, I don't think it's going to hurt anything, as long as you don't over-do things (most snakes don't prefer bright light, & you need to monitor for safe temperatures always.) I don't know off-hand of any major scientific studies on this, I think the evidence is mostly anecdotal. *The natural sun is far more effective & powerful than an artificial UVB light, plus, they're only "good" for about 6 months (last I heard?)- it's not that they burn out in that time frame, only that the UVB output diminishes.
Personally, I just take a stroll outside for sunshine & holding my snakes (one at a time) when I have time, weather permitting.