Is it necessary to say good morning to the girl you like every day?

It is necessary. The first is politeness (plus points for a gentleman) and caring about her performance (she will feel warm). At the same time, after a long time, it may become an involuntary dependence (that is, very good).

It's not necessary. If you are not a good friend or girlfriend, in this case, you can do it twice at a time. Too many times, she will think you are bored, and if you are poor in words, you will know those two sentences.

In a word, it depends on your relationship.