Are you placing park benches on lots or in the world?
If you place them in the world and not on a lot, the sims will high tail it to those benches to sit and eat or read. It doesn't matter how far they have to travel - they will get there one way or another!
If you are wanting them just for looks, I would make a tiny lot for the benches.
https://i.imgur.com/QYDWBGu.jpg
As you can see, you can make a tiny lot that is like 6x3 or even 4x3 and place your bench and then your sims won't act all crazy trying to reach that one that's in the world. (this bench is on a larger lot, just using it as an example.)
I also used rabbit hole rugs on the lot to make it a city hall, journalism office, vault of antiquity, arboretum and threw in a cafe ; ) It's a makeover of the Daffodil House from Champs Le Sims.
