Consider what happens when Eric, an electrician, replaces a failed motor. Being diligent, he checks the gearbox and finds it's low on oil. He fills it with 140W gear oil from a drum in the maintenance shop, and also greases a suspect bearing.
Because Eric used grease that's incompatible with the grease already in the bearing, that bearing will soon fail. Because this gearbox requires 90W gear oil and he used a much heavier oil, several problems including increased motor current will result.
Cross-craft training would have prevented this, but so would have another type of training. Eric's errors were in preventive maintenance (PM) actions. If he'd understood that all PM work should be done via a PM work order, he wouldn't have made these errors. Why? Because the PM work order shows which lubricants to use. Train maintenance techs to use the PM work order system, even if the PM work is part of a repair.