Not me, but I know a few experienced day traders — none of which uses a mobile phone or tablet as their main trading machine; just desktops and laptops. Though they use their phones to check out the charts when they're out and about(when we're out to dinner or a night of drinking), 99.9% of the trades occur on their Windows/Mac devices.

Safe to assume that it's simply because it's significantly easier to do charting and look at multiple charts on a computer than on a phone.