18 credits during Summer

Has anyone taken 18 credit during summer semester (9 credit a block)?

I’m planning on taking 9 credit a block and even thought I not a procrastinator and I will not work during this time I have 3 kids and I have never taken more than 9 credit a semester (only because of the fear of failing a class). I only have 4 semesters left to finish my B.S. degree. I’m thinking of doing this so I can do an internship next spring.

I want to hear from people that have done this.

How did you do? Is it doable? What was the hardest thing? What is something you didn’t expect? Would you recommend it? Something that I should know that I’m not thinking about?