How do you keep constituent data clean when most data entry is done by rotating volunteers?

I assume the user has forgotten everything since their last shift, and design for that rather than for the training day.

1. Constrain the entry path. Guided, staged data entry — an OmniScript or a well-scoped screen — beats a full record page with sixty editable fields, because it removes the opportunity to be creative.
2. Default aggressively. Gift entry templates and batch-level defaults mean a volunteer entering cheques does not have to decide the designation or source code for each gift.
3. Prevent duplicates at the point of entry rather than cleaning them later. Duplicate and matching rules tuned for constituents, not the out-of-the-box sales defaults.
4. Write job aids that fit on one screen and live where the work happens, not in a shared drive.
5. And accept that some cleanup is permanent overhead. I would budget an ongoing data stewardship routine rather than pretending a one-off cleanse is the end of it.