Cricket

I’ve never really understood the idea of a nightwatchman.

You're far more likely to get out at the start on an innings or a new day (or a new session) than when you've get your eye in after facing a few overs worth of balls.

So an opener going in for one over at night and then again the next morning is only increasing their chances of getting out.

Losing a wicket (i.e. the nightwatchman) in the final over ends the days play, so the opening batsmen that was being protected is safe for the next morning.

If you're going to lose a wicket then it's better it is a tail ender than an opener. If the nightwatchman survives then it becomes a problem for the bowling team as they're expected to get him out quickly the next morning, the more time he stays around the more demoralising it is for the bowling team and helpful to the batting team as he's taking the edge off the bright red cherry.