I just don't like the fact that they don't double or halve as I would expect which makes me wonder if I am right.
Puki: Warp is a logarithmic scale.
In the new series the creators decided to re-invent the Warp speed calculation so that Warp 10 was the theoretical maximum
Not theorethical maximum, but an un-attainable infinite speed. Of course they broke that one too, in Voyager.
But even in TNG they violated their new warp-scale again -- in the final episode, there's some (alternate?) future bits where riker calls for Warp 13.
(Let's just write that one up to dramatic effect)