> with thousands of bombs over months?

Say what now?

  Tokyo was bombed by the United States Army Air Forces (USAAF) ..

  The strikes conducted by the USAAF on the night of 9–10 March 1945, codenamed Operation Meetinghouse, constitute the single deadliest and most destructive aerial bombing raid in human history.[1] Sixteen square miles (41 km2; 10,000 acres) of central Tokyo was destroyed, leaving an estimated 100,000 civilians dead and over one million homeless.

> Do you see a difference in razing a city with one bomb in an instant or with thousands of bombs

Tokyo vs. Hiroshima - https://blog.nuclearsecrecy.com/2014/09/22/tokyo-hiroshima/

Do you?

(Aside from thousands of conventional bombs being significantly cheaper and lower tech than a nuclear bomb).

The human suffering in both cases is the same but one ended the war while the other did not.