timer-max-repeats

timer-max-repeats is a variable defined in `timer.el'.
Its value is

10

Documentation:
Maximum number of times to repeat a timer, if many repeats are delayed.
Timer invocations can be delayed because Emacs is suspended or busy,
or because the system's time changes. If such an occurrence makes it
appear that many invocations are overdue, this variable controls
how many will really happen.

You can customize this variable.