That's strange.
I just tried them, and the first one isn't working right now, but the second one is working fine for me. There are tons of references online that say exactly what I posted (I copied and pasted it). When taking a polygraph exam, only three relevant yes or no questions can be asked. After that, the results become less reliable. Thus, further testing should be done. (Beyond looking this up online, this has been my experience IRL, which is how I knew to look it up and provide cites for everyone).
Here is a different link and a different answer. Try this one:
(Bolding mine)
How many questions can be asked concerning an issue on the exam?
Validated polygraph techniques concentrate on a single or specific issue (e.g. infidelity, robbery, murder)
and can contain up to three questions relating to the issue to be examined. Other questions are asked on the exam which do not relate to the issue directly, such as, "Are we in the United States"? The purpose for all examination questions will be explained in detail during the polygraph pretest interview.
LINK:
http://www.imbordinopolygraph.com/faq_examiners.htm
And one more site. This is the 4th one I've provided, with a different answer -- but they all say the exact same thing -- 3 questions only (not including the control questions).
How many questions can I ask? (back to top)
The most accurate test which can be conducted is the one-question (single issue) test, but most clients are not satisfied with having only one issue resolved.
Slightly less accurate is the multi-issue test in which the examiner can cover three (3) relevant questions during a single examination, as long as these questions are related to one another (see #4 above). These three questions will take one to three hours to cover effectively due to the extensive test process required.
If more questions must be asked, another exam must be designed and conducted following the first one. This usually adds to the time and cost involved. Additionally, an effect called "anti-climax dampening" makes test results less reliable with an increase in the number of relevant test questions. It is the client's choice whether to have a single-question test or a multi-issue test, considering the difference in accuracy (see #1 above). Finally, a healthy individual can only produce readable polygraph charts for a limited period of time. After this time has expired, it is impossible to generate a conclusive polygraph test and any further testing must be scheduled for a different day.
LINK:
http://www.polytest.org/work/polyfaq.htm#howmanyquestions
If you play around on google, you will find a TON of sites that explain polygraph testing. They all say the same thing, though, I've found. Hope this helps.