Is it OK to skip running tests on master branch if "branch up to date before merging" check is enabled?

Hey there
We have the “Require branches to be up to date before merging” feature enabled on our github repository. Each time a branch is changed we run tests as a part of our CI process. The tests take some time to run and we would rather not run them for nothing.
Does it make sense to disable running tests on master branch considering the fact that the “Require branches to be up to date before merging” feature is enabled?
Is it correct to assume that since the branch was up to date when it merged and tests passed on it the master branch will pass tests as well (hence running tests on master is a waste of time)?
Thanks