I have a close to 4 hour train commute per day and I just bring my 15" laptop on the train with me. I have a laptop section in my backpack so carrying it isn't

I have a close to 4 hour train commute per day and I just bring my 15" laptop on the train with me. I have a laptop section in my backpack so carrying it isn't an issue. Being on the train is typically the only time I bring my laptop out of the house as it is a long ride to work on side projects. If I had to do more travel, especially on a plane, then I could definitely see how a 13.5" screen would be worth it.