Before I tell him he's wrong, I want to know what process he's ignoring.
There's a difference between somebody finding a more efficient way to perform a task and somebody deciding that company procedures, chain of command, customer requirements, or construction sequencing don't apply to him.
If he needs a tool, does he bypass the purchasing process, buy whatever he wants, and leave somebody else to straighten out the paperwork? Does he skip his foreman or superintendent and go directly to the customer or owner? Is he changing the construction sequence because his way is faster for him, even though it creates a problem for the people working behind him?
Those aren't necessarily efficiency improvements. Sometimes you're just moving the problem somewhere else.
Sequencing matters because we're not only trying to complete today's task. We're trying to create a repeatable workflow that other employees can understand and follow without creating bottlenecks for the next person or the next phase of work.
There's also a leadership issue.
If this is one of my strongest employees, people are probably watching him. That means what I allow him to do becomes part of what I'm teaching everybody else.
If I tell the crew there's a process but let my best employee ignore it because he's fast, I've created two standards: one for him and one for everybody else. That's bad leadership and bad training.
Now, if he's found a genuinely better way to do something, I want to hear it. A process shouldn't be protected just because that's how we've always done it. Show me the improvement. Let's make sure it's safe, meets the customer's requirements, doesn't create problems somewhere else, and actually produces a better result.
If it does, maybe we need to change the process.
But until we change it, one employee doesn't get to quietly create his own.