Example in the sched module shows the following output:

930343690.257
From print_time 930343695.274 positional
From print_time 930343695.275 keyword
From print_time 930343700.273 default
930343700.276

But since "keyword" is scheduled with a higher priority (lower number), it should be printed first.

URL: https://docs.python.org/3/library/sched.html
Section: 17.6

Though the delay arguments of keyword and positional are both 5, but their register time has tiny difference: 930343695.274 vs 930343695.275, so positional is printed first.

Sorry, it's not 930343695.274 vs 930343695.275. I mean the register time is time.time() + delay, so there is tiny difference between the two. You can change the timefunc to lambda: int(time.time()), then you'll see keyword is printed first.