Never thought about it, but smoothie users and likely grbl you can set max power below 1 or 255 to better protect the tube. I set mine at .8 (smoothie) and running my setting for power to 100% keeps it below 15 mA. If this is well known sorry, but feel it could be useful in protecting the tube from being over driven and life shortened.
There’s also a max pwm you can set in the smoothie config. So the difference would be: setting 0.8 in LW would scale in that range. Setting it only in smoothie would just limit anything over 0.8 to 0.8.
If you set all 3 you would get:
30W X 0.8 = 24W
24W X 0.8 = 19.2W
19.2W X 0.8 = 15.36
You can see how quickly the maximum power level decreases if you are not aware of the settings and how they work.
I have helped at least 5 people in hangouts get their power levels set correctly. I hope to add a wiki page this weekend about how to do it correctly and achieve the result they wanted. IAnd I almost have the rewrite with LW graphics for setting white to black raster power levels based on Mr Beam instructions.
I have been holding off on a lot of stuff until @Sebastien_Mischler is further along with his optimization of LW3. If you have a list of pages you would like me to create, or even just some general ideas of what you want in the Wiki, please send me a message and I will get on them.
OK will get a hold of him tomorrow. Will post a question asking users what documentation they would like to see added. Should give me something to do for a week or two…lol. About your comment of replacing the documentation guy (on my knees wringing my hands, teardrop gently rolling down my left cheek) “Please don’t fire me boss!”
@funinthefalls me first! (You have plenty to do!) 
Personally on my so called 40w tube I don’t go over 10ma for anything I do… I don’t mind making faster passes at lower power a few times it keeps the kerf more predictable and generates alot less smoke, so I don’t have to clean my optics as much, which always ends up leading me to realign all my mirrors
Because of passive cooling it also helps keep my water at a more stable temperature
I was going to ask just that +Peter van der Walt .
It works different on Grbl. The value you set in max pwm ($30) of Grbl represents 100% pwm and doesn’t reduce the max power. My suggestion: set $30=1000 (default) and limit the value in LW3 settings / gcode “PWM Max S value” to something like 800 (80% of 1000). Just be aware that you loose 20% of the dynamic range (0-255).