$Variable vs. preset ? when to use one or the other

#1

I am presently setting up a number of pistons that will be time of day sensitive.

I have read a few posts where people were encouraged to use presets instead of variables but, didn’t find a much explaining why.

Looking at sunrise and sunset for example, why might one use a variable or a preset? When is the variable sunset a better choice than the preset or the reverse, the preset a better choice than the variable?

#2

They both should result in same information. However, if you are writing an expression that needs other $variables you don’t have access to the presets

Ie.

‘The time is ‘ {$now} ‘ and sunset is at ‘ {$sunset}