You asked a question, which, only you are deemed suitable to answer.
As for customary practice, here in my region, we do not tip golf instructors, owner or not.
Why would you want to tip anyone? Because either you don’t believe they get paid in proportion to their effort or because you think they had done you a favor by extra service or advice ?
I would “tip” someone, during Holidays season, a gift card, a bottle of wine, home made cookies… someone who serviced our vehicle all year round, someone who did work for us on a regular base, and those who put in the extra effort during this difficult time for all of us. I normally do not tip hair dresser, but we did during this time, so with the take-out food order, usually no tip for take -out but we’ll leave a small tip.
For golf instruction , if the instructor feel that he is not being compensated for the hours and the effort, then, best to seek else where for employment or change profession.
However, if they had gone out of their way beyond performing their duty for paid service, then it is totally up to your discretion if and how much you want to “tip” them, and the form of tipping. It is not necessarily “instant” gratification, it can be in a form of returning the favor with your line of work in the future. Barter system if you like. Someone did you a favor , a returned favor is in order.
Not proper to tip someone for performing within their frame of duty which is owed to you.
Unless, you’re a philanthropist.
