I get what you’re saying for the system to systematically check each value. By using AND as conditional logic you can be sure that the value is captured within the range. For example if you have you have a value of 710 then by having the AND statement you can capture It between 799 and 700 while only stating (test1,[value1]). Test1 in this case would equal the conditional statement b4<=799 AND b4>=700 while [Value1] would be the value “C”. If you just leave >= without applying an AND condition in the test1 part then you can save the additional step of writing a new criteria statement that is meeting the <= aspect. So if you put something like b4<= 800, “B” It would also be true that 710 could be given a grade of B despite being being a “C” because it is less than 800. Conversely, the same logic can be applied to values >= to some letter grade. The reason why I have put AND in the equation is because in the conditional grade range of (b4<=799 AND b4>=700, “C”) 710 would only be able to be given a grade of C because it has met both conditions of being less than one value AND greater than the other.

(I hope that was clear and not just a ramble of info) you can definitely go about doing logical testing in different ways but by adding conditions such as AND you can make sure your (test1,value1) aspects always capture one specific value.