In The Expanse series, characters experience sustained Gs during space travel, not just during acceleration, which doesn't make sense. For instance, here's several passages from Leviathan Wakes, the first book in the series (tried to omit anything that could be a spoiler):

Walking through the Rocinante felt surreal. [...] To walk through the spare, functional corridors, thrust gravity holding him gently to the floor...
[p 359]

And:

Alex had the Rocinante running at three-quarters of a g for 2 hours while the crew prepared and ate dinner. He would run it back up to three when the break was over [...] Once the gravity had dropped from the crush of high acceleration, the whole crew quietly gathered in the galley...
[p 366]

Both passages suggest that there are more Gs during acceleration, but always some amount of g-force just from moving. However real-life physics dictate that you feel g-force only when you accelerate. If you're driving on the highway at a constant speed of 80mph, you aren't being pushed back into your seat. How is the Rocinante generating constant g-force, unless it is constantly accelerating? After hours and hours of travel under any amount of g-force from thrust, wouldn't the speed become unsafe? Or is there something I missed?