For 500 word sections (log, intro and conclusion) the 10% rule does apply, so you may go to 550. Beyond that, you need to cut it down - 600 words is obvious. While you may not write the number of words on the page, markers are reading dozens of PIPs and they know exactly what 500 to 550 words looks like, so it's very obvious when you go over. The central material gives you such a broad guideline (2500 to 5000) that you are NOT to go over 5000 words for that - again, markers know and you may be penalised. Markers are looking for your ability to synthesise disparate information and be succint, so if you are meeting the outcomes there should be no need to go over 5000 words.
Hope that helps! Good luck!