Feature branch dependencies with Gitflow

We are using Gitflow http://nvie.com/posts/a-successful-git-branching-model/ as our way of working and developers keep saying they always face the problem that the next function builds on the latter (adding new functions), so I told them that they can detach the previous function, work locally and when the previous function is approved (pull request) then they can rebuild based on the dev branch, so it looks nice in history, but they don't like it, so they offer an integration branch so that all the work is based on that and then they merge back the integration and then issue a pull request to the development branches so that this way they always work on the latest code.

What do you undertake?

Yes, I know that dependent work is not good, but I don't think there is a way to get around this, I mean you create a function on previous work, and if that work is not good, you cannot do it.

It's also possible that our features are too big, but I don't think so, we use 3-4 days for each developer per branch before we usually issue a pull request.

donnib