I'm thinking currently about the Create Account Process on a mobile app. Is the preferred way for the user to fill all his credentials (Username, E-Mail, Password, Confirm Password, Birthdate, Gender) on a single screen or is the UX for the User better if he gets guided through the steps with individual screens?
I think it depends on the number of fields you have. If you're asking for some basic inputs like username, email, and password, I think it's reasonable to have them all on one screen. Anything more than 5 fields would best suit 1-3 screens HOWEVER...
Of the several signup flows I've designed, I prefer to always default to using several screens based on the context of information you're asking for, for example:
- First and last name can be one screen.
- Email can be a single screen.
My reason is that on a mobile device you get the keyboard that slides up from the bottom, so it obscures the content further down the screen. Scrolling isn't a huge issue, but it's easier to just type in your field and navigate to a new screen with out everything jumping around.
There are some best practices for using multiple screens like always making sure they know how many screen to expect, and give them some progress on where they are in that flow. If you're asking them to set a password, make sure they know what rules you need for them get it on the first try (you don't want a error popping up after they've entered it), and allow them to see the password as well - hidden passwords are just stupid. Make sure you trigger the write keyboard as well, for example when entering an email or a phone number, have the appropriate keys like '@' available without having to tap 'shift'.
Hope that helps.