Final answer:
The best rule for adjusting speed in traffic is to maintain a speed that corresponds with the flow of traffic, without exceeding the posted speed limits, ensuring the safety of all road users.
Step-by-step explanation:
A good rule for adjusting speed in traffic is to try to adjust to the flow of traffic, as long as it does not exceed the posted speed limits. It is important to note that while sometimes traffic may move slower or faster than the posted speed, it is the responsibility of each driver to adhere to speed limits as they are legally enforceable and designed to ensure the safety of all road users. If everyone is speeding, it does not make it safe or legal to do so. Additionally, in certain traffic situations such as congested areas or where construction work is taking place, it might be necessary to go slower than the posted speed limit for safety reasons.