How many fieldmaps do you collect in a session?

Hi all,

I am about to begin a study that involves a single imaging session between ~75 minutes long, including anatomicals, task-fMRI, and DWI. I have seen different protocols handle fieldmap collection differently. Some just do one fieldmap for the whole run, and others may do one set of fieldmaps before each BOLD/DWI sequence.

I am curious if data collectors here can speak to their experience of whether it is worth collecting a fieldmap before each sequence, or if fewer is sufficient. Thanks!