Quote from comments here:
If you say "My goal this month is to add Stripe payments" then you (or your team) is absolutely going to obsess on that. That's the goal and that's what should be shipped.
The problems start when unknown complexities are discovered. The API is missing some params, you need to deal with annual plans a certain way etc, or they don't support the type of subscription you want... The team will spend time looking for ways to solve the Stripe integration because that's the goal.
Now, if you put "get XX paid customers" then things are different. When faced with hurdles you can start pondering if you should keep going with Stripe or if you should pick an option B. Perhaps you can just charge customers manually, or perhaps there's another service that can be a better fit.
Deliverables (Stripe integration) and impact (getting revenues) are 2 different things. Yes you should absolutely track your deliverables, but it's much better to focus on impact when listing your milestones and goals.
It's incredibly easy to get sucked into an interesting technical problem. Keeping the bigger picture in mind makes it easy to make tradeoffs — at the end of the day we do the technical work to move the needle in specific ways.