Can I disable key checks and, if so, how?

You can do it, but it's not recommended for most users

By default, Unchained multisig vaults have a key check feature enabled, which involves quarterly check-ins for each of the keys that are part of your multisig vault or loan. We strongly recommend that you perform these checks every 90 days to ensure you maintain access to the keys that are critical for accessing your funds over time. 

However, if you understand proper security best practices, would like to disable email notifications to check your keys, and don't want to perform key checks, you can do so by following these steps:

1. Sign in to your Unchained dashboard.
2. Click Keys and click View to navigate to the proper key in the Unchained dashboard.
3. In the Key checks box, click the three dots drop-down menu.
4. Click Disable Key Check.
5. You will be presented with a disclaimer that looks like this:
6. Click Disable Key Checks.
7. That's it! Key checks have been disabled for this key.