I recently shared a Chateaubriand with my best mate at a restaurant, he was pushing for it and I was dithering in my menu choice so he ordered it, taking a liberty that only a best mate can get away with
It was fine really we got out own sides and the waitress divided the meat for us so after that, it was like your own meal.
Wouldn't normally do it with this sort of food but no issue with Chinese etc.
Only other time I "share" is with desserts, I tend to prefer a starter, my wife likes desserts more, so after she makes her choice she then picks her 2nd option for me. When they arrive we give each other a bit of each dessert.
If I'm out on my own or with work seldom bother with desserts.