Hello all! New to this forum, old to Nissan!

Prev owner of a Max, Sentra, Path 98 & now own a Path SE '01. My prob? "Serv Engine Soon" lite on & mechanic had it re-set
& lite off. Took it in 4 NYS inspection & failed due to emission fail. Exhaust sys completely rotted out & had it replaced. Back 4 inspection & "catalyst, Evap system cleared & complete" but Ox sensor reads incomplete. Mechanic states to drive vehicle for 60 or so miles for it to re-set & drove aimlessly

for over a 100mi yet last & final reading for emission test states "Ox-sens" incomplete. Mech says that I need to drive an addtl 20-30 miles in "smooth" hi-way traffic in order to re-set sensor for "complete" code to appear (I told Mech that in NYC, there is NEVER any smooth hi-way traffic)! N-e way, is there anything I can do to "speed" along the completion process of the last & final portion of the emission test which computer still shows "incomplete"? Thank you!