If a guy living in an oppressive country such as Saudi Arabia visited an atheist site, for instance. 5 years later, would you tell him that there's a high possibility the ISP deleted the evidence of that from their servers or would you tell him to travel abroad and stay away? Just hypothetically.
In Saudi Arabia, the ISP (CITC) blocks access to prohibited sites. If some website is deemed haram, you can't get to it. CITC is not omniscient, so it is possible that a site which could be forbidden, and eventually is forbidden, is not at some point forbidden.
There are various laws against hacking and requirements to safeguard information, and the Telecommunications Act in Chapter 10 enumerates various forbidden acts (providing unlicensed internet access etc), and prohibits (18)
Other than in the course of duty, intentional disclosure of any information or contents of any message, which has been intercepted in the course of its transmission
I will not attempt to interpret that: I believe that it means that it is illegal to intercept a message except if officially required to. An IP address is not a message (anyhow, the law is written in Arabic so we'd have to go to the actual text). In other words, there is nothing that would prohibit the ISP from handing over "who touched this site" information to the mutawwi`. There is also, from what I can tell, no law requiring them to retain such information. CITC makes a lot of information available online here. Article 7 of The Anti-Cyber Crime Law may make such access to a website illegal. In other words, there's no way to be certain, save for getting sworn testimony by government officials.
Answers for other regimes would no doubt be different in details.