Is it normal that some friends haven’t spoken or seen each other in like let’s say 2-3 months?

I mean I work and go to school. I work from 7am to 3:30pm. Then I take my two classes so I’m very busy. The last time I talk to one of my friends was like almost a month ago. Where is seen each other since January but will make some time to hang out but we’ve been so busy. Ask mother asked her if she wanted to hang out but she says she had plans which was totally OK. I’m like 28 and she’s 24.