Deadlines!

Even though there are deadlines, never work on weekends.
In fact, when the deadlines are coming near, disappear on leave, until the deadline is over!
There are several benefits of following this approach
a) your backup resource is built automatically
b) Once your backup resources are ready, any leave in the future will get approved very easily too; since your manager knows who can do your work in your absence!
c) Since you are likely to disappear on leave suddenly, nobody will make you a backup resource for others!