Hi Andrew, I reported in November 2025 issues with callbackRequestDelayed returning essentially immediately for delays less that 0.01 second. I am happy to report that this works fine in base 7.0.10 on Linux and Windows.
cf. github issue 106 and PR 704. There is even a release notes entry!
https://github.com/epics-base/epics-base/blob/c5d1668895094bea44aee7655c386b2d9192cfa9/documentation/RELEASE-7.0.10.md?plain=1#L373-L389
... ... I changed sscanTecord.c to remove that restriction except for vxWorks. ...
This tracks well with the change to epics-base.