JBL L100 Classic to 4 or 8 ohms ?

The same thing happens to me.

How many hours does the woofer need to break?

Did you feel any change with the hours? Did you try again with 4?

I'm surprised with the woofer size and only goes to about 60hz-70hz, maybe need more hs ?

One should always try the various ohm settings on your amp and decide for yourself which sounds better. It's not going to hurt the amp or the speakers.

I supplement my JBL speakers with a single SVS PB2000 sub.  It makes a big difference, I also use a Schit Lokius 6 band EQ

2 heavy 12`woofers need sub ? 

I had a pair of JBL L100 Classics and they definitely needed a sub (or two) since they roll at about 70 hertz.  That 12" is more of a low mid driver than a real low frequency driver.