Engine break in without a tachometer

I swear my wife has more experience breaking in cams than most people I know LOL even when I have her run the drill on the oil pump and I turn the crank she says oh there it is! Knowing when the drill speeds up a little bit that it's oiling one side. She'll start the engine and let me work the throttle and get the idol turned way up. She watches the temperature gauge in the oil gauge and reports... Sometimes I'll invite a friend over who knows what they're doing. Most guys don't want to miss an engine break in...