In most games, friendship evos require a friendship of 220 or greater to evolve. However, the friendship checker in most games uses a chart similar to the one below in order to decide what message to give. Since the second-highest range starts at 200 and ends at 254, you can't necessarily use that message to tell that a Pokemon is ready to evolve (unless you've gotten it all the way to 255).
View attachment 417383
This is changed in Sword and Shield, where they finally changed the highest interval to 220-254.
View attachment 417384
However, they changed the evolution requirement to 160 friendship at the same time, which is
not on the bound of any of these intervals, meaning that the friendship check message still cannot be used to (precisely) determine when a Pokemon is ready to evolve by friendship.
Sure you could just wait until you've reached the next highest interval, but why not just put the requirement at 180? That way there's a good in-game indicator as to when your Pokemon is ready to evolve. (Some checkers use
alternative intervals, but there aren't any with an interval that starts at 220 except for in Sword and Shield)