Would you have your portfolio on your person at all times? Probably not, but you wouldn't go on a long trip without it. If you were actively working you'd have it available. If you didn't have it, you'd accept the risk of losing a contract or having your work temporarily withdrawn from sale. Maybe a bookseller would notice typos in your current edition and takes your book off the shelves until you can make a revised edition.

I mean, fundamentally, if you're saying your book needs to be on sale 24/7/365 then you need to be standing behind it 24/7/365 or paying a person or organisation to do that for you. If you want to take a break from the business of your book you should be prepared for Amazon to do the same.