A touch-up chisel filing seems quicker and easier for me, but I've been doing it for 40 years. Besides, my chains can normally work all day without needing a touch-up.
It takes a long time to learn, though, and I'm still learning.
I have limited experience hand filing square cut chains. IMO, it is not that hard and some variance from cutter to cutter is not going to wreck your day. Practice makes perfect, so don't be put off when your first attempts don't match up to what your round file can do. Round filing also had a learning curve, so why wouldn't the square filing too.