The idea is not a casual cruise.
Move with the traffic to be safe and promote safe driving down the road.
This is particularly important in heavy traffic areas. You may not be able to get to the minimum posted speed because semis are dwelling in the left lanes and Mom just picked the kids up from school and she never drives over 45 and to heck with being an impediment and safety issue.
There are some roads where I Sunday drive around here and in the Country but I won't back up traffic.
I've been cut off, in the right lane many times and the left lane. Wife is constantly because she refuses to go at the prevailing rate, some times, of traffic. I have to get her to move over. It matters not how fast the others are going. Your safety and not creating a safety hazard on the road is of paramount importance.
If 55 is all you can go and that is the limit stay in the right lane.
I had a woman from Alabama, the other evening sit in the left lane. Every time there was clear space in the right she sped up instead of getting over. Then she would slow down to match right lane traffic. Flashing lights didn't bother her, except maybe to call Leos and complain someone was bothering her.
When I got off the Interstate there was a long line of traffic back up behind her.