Metadata Question

Hello all!

I am currently working on an architect's SEO right now and I'm in the process of rewriting her Meta Descriptions. She has 17 projects listed on those 17 pages (they are galleries of her residential and commercial work, each page has a couple of sentences detailing the project). Most of them do not have meta descriptions, some have descriptions but they don't feature strong keywords, and I have a few general duplicated descriptions (i.e.: more than one page's meta data saying "we are a multidisciplinary firm and we are amazing").

My question is, do I need to write out a meta description for each project, or should I just leave them blank and let Google do its thing? I've heard conflicting answers: some say you don't truly need meta descriptions for each and every page, but others say you should do it. Her site doesn't have that many pages and I enjoy the writing process, so it's not an issue if I need to do them all (and if it'll increase traffic) — just looking to see best practices as I gain more experience.

(Edit: Tried to make the title a little more descriptive — alas I forgot you can't do that.)