I think there's good value in paying someone to check over the system annually, simply to cultivate relationship.
Over time the HVAC professional will have opportunity to get familiar with your equipment, and you'll have opportunity to become comfortable with the professional. Then, once emergency occurs, you'll probably be treated, at minimum, fairly.
And also I think your opportunity to maximally receive benefit of the doubt, and support, in warranty repair situations, is substantially enhanced.
I'm not convinced it's worth taking this to twice per year, though, as is customarily emphasized by the HVAC industry. At least with the packaged GSHP systems, they're pretty simple and straight forward devices, with not a lot to break.
Religiously changing filters, looking over the system occasionally for water leaks, and cultivating relationship via a once per year visit from an HVAC professional, in summary, I think are actions that maximize return on investment for GSHPs.
Best regards,
Bill