Parent/Child events help a lot in terms of code readability, and also slightly speed up your project because you don't have to test for the same condition every line.
IF X = True THEN
IF Y = True THEN DOSOMETHING1
IF Z = True THEN DOSOMETHING2
IF I = True THEN DOSOMETHING3
Both examples have the same effect, but in the second example, X is evaluated 3 times versus once in the first example, which leads to slower execution. BUT activating groups is a totally legitimate alternative.
IF X = TRUE AND Y = TRUE THEN DOSOMETHING1
IF X = TRUE AND Z = TRUE THEN DOSOMETHING2
IF X = TRUE AND I = TRUE THEN DOSOMETHING3