A complex form, split into 5 steps using the material design stepper, step 4 is optional. should this screen have a 'SKIP' button and a 'NEXT' button, or just a 'NEXT' button?
If a step is optional in the user journey, there must be affordance for the user. However, I usually find it annoying to see it being optional right at the end, after I've filled out the form. If you can inform the user upfront about the step being optional, it might help create a better experience. Here are a couple of options you can do:
- Adding an 'Optional' tag in the step indicator
- Adding a notification at the top of the dialogue
If step 1 have to be completed before step 2, and step 3 before 4 etc... Then: I will start from disabling 'NEXT' in 1, 2, 3 and 5 step. Once user complete the task 'NEXT' is unable. When user get to step 4, the 'NEXT' should be active whole time. It inform user that he/she can jump to next even if the user didn't completed the step 4. You shouldn't leave 'NEXT' active for steps that have to be completed, it is confusing.
Do you want your users to be able to go back and forth in wizard even when steps aren't completed? Then usually it is solve by a disclaimer "this step is not required". Although then should be some default settings for all steps, because you allowing user to basically skip it all. (Like when you install a program.)