I am dealing with this same issue - we have remodeled 3 bathrooms in the last 2 years. The master bedroom has a shower head from the ceiling, but the second bathroom uses the shower head you described. Like yours, the measurement is 80” from the wall, not the shower head. Ours lost 5”. If you hire a firm who has their own in-house designer for free and when you have bought the shower head and it’s sitting in the garage before the tile goes up....I say the client always wins and it’s on them to fix it. This is why contractors charge you a 40%+ mark up on labor. Expect it to be done right the first time. No exceptions.
I am dealing with this same issue - we have remodeled 3 bathrooms in the last 2 years. The master bedroom has a shower head from the ceiling, but the second bathroom uses the shower head you described. Like yours, the measurement is 80” from the wall, not the shower head. Ours lost 5”. If you hire a firm who has their own in-house designer for free and when you have bought the shower head and it’s sitting in the garage before the tile goes up....I say the client always wins and it’s on them to fix it. This is why contractors charge you a 40%+ mark up on labor. Expect it to be done right the first time. No exceptions.