It's hit and miss. Sometimes he loves his dad (generally tied into when he bothers to plan something child friendly). Other times he's just dumped by his dad on older relatives during his contact time. Or his dad is late to collect him and then DS just doesn't want to go.
Selfishly it's my only free time (to do extra work/housework) and I don't discourage him from going but at what age don't I force him?