On small fixes, it comes in handy to be able to separately deploy front end code, API Gateway code, or different back end lambda groups. But other times, like big feature additions, most of the repos have new changes, and I need to push an entire environment.

Part of this is an artifact of using lambdas and serverless.com. Serverless deploys all the lambda code in a repo to each lambda. It doesn't try to parse which code is shared. If I add too many lambdas to a repo, deploys take longer and I run into the AWS lambda code size limit.

But I also don't want a repo for each lambda because then I'd have to automate a ton of stuff that's currently manual, and for our tiny shop I think that would be overkill. We'd almost need a dedicated automation person.

We also have repos for several react front-end web apps, and the AWS API Gateway code that connects the front end to the back end. It's very common that I only deploy the react web-app. I have no idea how I would do that in a mono-repo that had all the front end, API Gateway and serverless.com/lambda code. I guess git tags? But I'd always be worried about screwing those up.