It's a mixed bag. He made strides at Fishman Island and post-sugar Dressrosa, did fine at Punk Hazard and Zou, stagnated/regressed in Wano and in Dressrosa before he knocked out sugar. Wano was really bad for Usopp. Luffy, Zoro, Sanji, Nami (Zeus), Chopper (lengthened rumble, cured Ice oni), and Robin made or received improvements. Jinbe and Franky scored victories. Brook at least did some solid work in Wano after being the low key MVP in WCI. I can't think of any significant thing Usopp learned or did during Wano.
Even though Chopper tends to get scared, his courage has grown exponentially as he stood up to Big Mom on the Sunny and fought Queen. Whereas Usopp hid behind Nami against Page One and Ulti.