In the thread you referenced in the above post you worte:
Since the venue gives the bride the top cake for their 1st anniversary, that means that it's my personal donation. I don't get reimbursed for the top cake at all (nor do the Chefs realize that).
That is the venue's choice to give the bride the top tier for their 1st anniversary, not yours. You need to have a talk with the chef and his boss to explain pricing and why your numbers and the chef's don't always match.
Also, if the bride tells the chef (who then tells you) 100 guests are coming and then 109 show up. That is not your problem. The chef can either cut a few pieces of cake smaller to squeeze some extra slices out or he is 9 short and tells the bride "you said 100 - we provided 100". End of conversation. She only gets what was paid for.
As pointed out in my above post, I round down my servings number. A cake that would feed 114 acccording to Wilton, I round down to 110. That allows for the missing dowel pieces or oops pieces. I always drop off a cutting guide. I don't care if the chef has cut 1000 cakes, I drop of the guide to cover my butt. If I tell a bride her cake will feed 100 and the chef only gets 60 servings, then I can point to the guide I dropped off and tell her with 100% certainty that either the chef didn't follow the guide or dropped/took the cake.
Wilton is the standard. If you want to provide more servings or larger servings, fine, but you are shorting yourself money. Which will lead to frustration and burn out because you are doing so much extra work for no compensation.