Simple Survey gives you the option to re-use questions in multiple surveys. Questions that are no longer in use can be manually deleted from the Simple Survey object in order to reduce the number of fields in an Org. You can reuse any field using a different Question Label, however, you cannot change the field type.

For picklist fields, you cannot switch from a global value to entered values and vice versa. In addition, all surveys get updated if any picklist value is added/removed.

As a best practice, we recommend deleting inactive surveys, reviewing questions periodically, deleting irrelevant questions, and re-using them where possible.