Any program that locks programs for certain times?

I'm instituting some New Year's resolutions around productivity.

One of those is to limit the frequency at which I check my email — and other communications channels.

I primarily use Rambox for this purpose.

I am looking for a productivity app which limits access to programs to either:

a) Certain times of the day
b) A cumulative period per day (e.g., one hour in a 24 hour period).

I've checked out some of the parental control tools but clearly these are intended for a slightly different use-case.

Does any program exist of this nature or is developing one — or developing self-control — my best bet?

Thank you in advance!