Depends, Good training will improve your riding but I’d ask yourself why do you want to improve, are you not happy with some aspect of your riding? Any type of training will be of most benefit if its well targeted.
I’ve thought about doing a course a few times but I just ride for fun and for fitness, so whilst I expect that getting some coaching could make me a technically better rider, probably faster or able to tackle trickier terrain I’m not entirely sure that i care about being faster or technically superior.
For me it’s the sort of thing that If I got given a days training as a birthday present I’m sure I’d go along, enjoy it and hopefully get something out of it but I doubt that I would ever consider it a need.