The following video covers some of my observations on the cheap metal-geared servos I use in my Otto builds. I have written a short Blockly calibration program and an equivalent sketch which allows me to calibrate using microseconds.
I also show two non-blocking 'sweep' programs that will allow for slow servo motion or a full sweep.
Note: @Birger T correctly pointed out that care needs to be taken writing microsecond timings to the servos outside of their 'limits'. These limits were well within the mechanical end-stop so did not put the servo under undue strain (you would hear it 'groan').
All code is attached. I can post a Fritzing if anyone would like to try this calibration method out.