Sometimes, while we're developing, we find solutions to problems that work correctly. And sometimes, we think it is the best solution and stop thinking of other possibilities.
I had a recent example few days ago, while I was coding a SQL Server stored procedure that filtered date ranges, returning elements that fit in the first four of this six available outcomes:
#1 - Wanted
#2 - Wanted
#3 - Wanted
#4 - Wanted
#5 - Unwanted
#6 - Unwanted
In order to acomplish the four first situations, this would be the SQL comparisons needed:
B1>=A1 AND B2<=A2
B1<=A1 AND B2<=A2
B1>=A1 AND B2>=A2
B1<=A1 AND B2>=A2
But, there's sometimes a shorter solution... Like this one:
A1<=B2 AND A2>=B1
Beautiful, don't you agree? Just by switching Bs we reduce to just one AND, covering all four desired causistics...
Sometimes we see a narrow passage (play with the lesser/greater operators) when there is more than one solution (playing with the Ax/Bx operands).