Absolutely effective for practice, I do it all the time especially when weather is bad and I'd rather shoot under cover than out in the rain where my long range targets are.
In one years time I went from 16th place at the local club match to top 40 in the PRS finale and the bulk of my practice was dry firing from a barricade I built and kept in my back yard. Your 100 yard range is an excellent place to practice. I recommend running your barricade drill at least 3 times dry firing for every one time you run it with live fire.
Any trigger time is better than no trigger time in my opinion! The range at my house only goes out to 200 yards I have steel setup at a 100 and 200 yards I have noticed I learn a lot more about what I am doing right and wrong when I am shooting paper at those distances. Just like @Sheldon N said the paper will always tell you where you are at. Steel will lie to you but paper will never lie.
I got into NRL22 this year for similar reasons. Long range is about twice the distance and my 200m range. My old Ruger 10/22 in a Magpul stock with a Vortex Diamondback scope running cheap and good shooting CCI SV ammo is a great way to practice positional shooting at 5¢ a trigger press.