If you bump up the gap the coil has to pump out more volts to jump the gap. Normally this can fail a coil internally (primary and secondary circuits melt together). As far as the icm i have never failed one testing the spark it probably has to do with age and maybe a shitty deigned.

The icm is just a switch that turn on and off the power to the coil. Switches fail over time and if thy are made with shity materials thy fail faster.