You’re at the supermarket. There are 8 self-checkouts and 15 people in line, there are 3 servers scanning baskets only with 5 people in line and 4 checkouts for trolleys each with 2 trolleys at each. Or you’re at immigration after getting off a plane, and you can see 3 lines each of different lengths, but it looks like they’ve just opened up another agent who’s only accessible from the right-hand line, but it already looks longer. Or there’s a jam on the highway but it looks like one lane splits into two up ahead. Or they’re checking passports at the gate and it looks like there are two people checking at one line and only one at the other.
OK, chances are we probably won’t get it right, and most of all it’s worth just making peace with that and not stressing about it. But, there are times when a little counting, checking ahead and some mental arithmetic can save you a little time and give you a little glow of satisfaction. Good luck.