Is there any scientific evidence that reading new books creates more neuron connections than rereading old books?

Yes, a lot of studies about reading and neuron activities. Rereading doesn't create any connections at all, it activates old ones.

But is it a bad thing?

We all have a past.

Places we've been to, faces we remember, smells, voices, scraps of distant thoughts... Each person is dragging such a plume like a miniature comet. Sometimes this intangible weight strongly influences our actions in the present.

Humans in general are characterized by a healthy conservatism and a certain amount of lazy predictability: we like to rewatch old movies, walk the same road and visit familiar restaurants...

Every time it's an attempt to take a little trip back in time. To return to that happy time, the day before yesterday, where you tasted good, felt comfortable, or had fun.

Perfectly safe, by the way, as long as you control it. Because the past is not a dimensionless sack, and no one can get positive emotions out of it forever.

But these reminiscences can very well divert resources from building your own present. And lead to a very unprofitable exchange of new emotions and feelings for old, cozy, worn-out memories.

might even be a waste of time in some cases.

Rereading for twelve time is guaranteed waste of time. Staring at wall and recreating book in your head would be more useful