It wouldn't take too long. In 30 seconds it could be done and I've never ever seen the outcome of a public match being decided within the first 30 seconds that had starting credits 0 (heck, it usually takes a full 30 seconds just to get to the enemy base on foot). Usually battles go on for 15-20 minutes, so a minute preparing to do something is not a minute wasted.However, it doesn't really work. The MCT only takes damage from C4 if it is placed directly on it - a C4 that goes off one pixel away does no damage whatsoever. Also, as previously pointed out, that C4 is better spent mining the base. Use a Hotwire/Technician to blow up buildings.