One at night. The LC-1 is pretty cool cause you can expand it with other Innovate boxes to log RPM, TPS, MAP, Boost, exhaust temp etc. You'll need a USB to serial adapter to program the refresh rate on the LC-1 and to log AFR.
Either get the one Innovate sells or here's one I got that works:
http://www.newegg.com/Product/Produc...82E16812107108
It's picky about serial adapters.