I have invited friends to my Club in the past for both pre-season sighting in and zero verification. Sometimes I am working on their equipment more than mine. I, too, use the 25 yd starting point when getting them started, and checking my own rifles/pistols.
Of course, I check their ring screws for security, and proper inch pound torque.
I also check their optic for rear objective focus and eye relief/shooting form before their first shot. I’ve had a few “magnum eyebrows” bestowed on my guests from their poor mounting; the butterfly strips and compression bandages in my range bag stopped the bleeding quickly.
Always happy to give guidance where I can, but I suppress my urge to interfere with my “assistance” if unsolicited.
I have certainly shot more paper over the last 57 years of range trips and multiple disciplines of Marksmanship pursuits, and I continue to do so. Likely the ratio is near 10K to each round fired to take a Game animal or Varmint.
Usually my guests or Fellow Club Members who are receptive to my offers are more than satisfied with the end result down range performance.
Of course, I have a bit of fun with them before we pack up, and the “Shoot for Guns” challenge is proffered by me. They chuckle when my T/C Contender Super 14 in .30-30 is my choice, but their amusement fades when my groups are smaller than their rifle’s at 100 yds. The look of worried consternation on their faces is priceless, but I let them off the hook with only my lunch bill

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They typically wind up on the range far more now that their equipment is properly secured/zeroed and likewise enjoy the experience more as well.
I was blessed with great tutors and I try to pay it forward.
GotRDid.