I'm pretty sure I have my SRM set at 1 second intervals. I'll download data after every ride or two and since most of my rides aren't longer than 2-3 hours, the 6 hour setup works well.
I do need to go back and read the manual since I kept going into interval mode while trying to calibrate it yesterday. I couldn't get out of interval mode, so I just kept pressing buttons till something else happened haha.