When I was working, employer matched every pay period with no make-ups, so not an option.
I used to be vigilant about tax withholding. Every year, when I'd had as much withheld as I owed the year before, I shut off the tap (changed status to Exempt). I then banked the difference and put it into non-retirement accounts. HR never understood why I was doing this (i.e. creating more "work" for them, but I'm pretty confident that they're all still working.)
I rarely managed to front-load my Roth either, because I'm a lazy ass. I know, I know, I could have so much more money by now if I did (blah x 3), but somehow I stumbled across the finish line with enough, despite my slovenliness. It matters most that you invest on a consistent basis, not that you front load.