Well, the answer to this question is easy and variant both at the same time. It relies upon the needs of the user who likes to count his space bar clicks.
According to personal experience and statistical data collected from many users, people tend to use 5 seconds space bar test and 10 seconds mostly. If you are a new user who wanna perform a quick test, these two timings are your best choices.
On the other hand, if you are a vigorous hardcore gamer, then a 30-second space bar test, 60 seconds, and space bar click test 100 seconds should be your choice.
Remember that, a longer time duration demands more focus and consistency while conducting your test. We’ve observed that people get distracted or lose tolerance in longer space bar speed testing.
