I suspect a large proportion of claims made for productivity increases are skewed by the fact that the speed at which code is produced by AI makes you _feel_ productive, but these gains are largely replaced by the effort to understand, refactor, review and clean up the code. The high that you get when something "works" tends to stick more in your memory than the time when you had to spend a day cleaning up dead code,…
I think it has a lot to do with the type of work you are doing. I am a couple of years into a very small startup that has some actual technology built (as opposed to a really simple CRUD app or something).
When I am working on the front-end where things are pretty simple AI is a huge speed up. What it does VERY well it latch on to patterns and then apply those patterns to other things. If it has a couple of examples you can point it to and say "ok build that but over here" the newest revisions of Claude and Gemini are perfectly capable of building the whole thing end to end. Because it's a fairly repetitive task I don't have to spend much time untangling it. I can review it and pattern match against things that don't look right and then dive into those.
For a real example, I needed a page for a user to manually add a vendor in our platform. A simple prompt asking Claude to add a button to the page sent into a mode where it added the button, built the backend handler, added the security checks, defined a form, built another handler to handle the submitted data, and added it to the database. It even wrote the ACL correctly. The errors it introduced were largely around using vanilla HTML in place of our standard components and some small issues with how it attempted to write to the DB using our DB library. This saved me a couple of hours of typing.
Additionally if I need to refactor something AI is a godsend. Just today an underlying query builder completely changed its API and broke..everything. Once I identified how I wanted to handle the changes and wrote some utilities I was able to have Claude just find everything everywhere and make those same changes. It did it with like 90% accuracy. Once again that saved me a couple of hours.
Where it fails, usually spectacularly, is when we get to the stuff that is new or really complex. If it doesn't have patterns to latch onto it tries to invent them itself and the code is garbage. Rarely does it work. Attempting to vibe code it with increasingly more pointed prompts will often result in compiling code but almost never will it do the thing I actually wanted.
In these contexts it's usefulness is mostly things like "write a sql query to do X" which occasionally surfaces a technique I hadn't thought about.
So my experience is pretty mixed. I am definitely saving time. Most of it is typing time not thinking time. Which is like 1/3 of my average day. If I had to guess I am somewhere in the neighborhood of 30-40% faster today than I was in 2019. Notably that speed up has allowed me to really stretch this funding round as we are well past the phase where we would have typically hired people in my past companies. Usually someone relatively mid-level to take over those repetitive tasks.
Instead it's just me and a non-technical founder going along super quickly. We will likely be at a seed round before anyone new comes in.