Giant numbers like 1 inch are used to cover all applications but type of suspension and wheel travel will change that number slightly.

A lowered road course type car with short shocks and stiff springs will require very little yoke clearance.

A lifted truck with long shocks will be on the breaking edge at 1"

With that said. Without bottoming the yoke out, less is better. It makes for a more stable driveshaft and high driveshaft rpm.

Most cars barely use up 1/4" of travel.