There could definitely be some improvement to the method, Donnie's ever-working mind already considering how much more effective he could have made it with a little more time. It might have just drained him faster. He hasn't tried anything like this and sustained it for so long, and getting out of immediate sight of the mining site takes even longer when you're trying so hard to cover your tracks.

There's no sneaking involved by the time he spies Angelika, but his footfalls are soft enough as it is that surprising her may not be intentional. If she were paying attention she'd make out his panting, but either way, he greets her with a breathless, "Hey." And then promptly collapses.