I heard Cloudflare development mode can be turned on for 3 hours only. Still, I do not find related information from the official document(see https://support.cloudflare.com/hc/en-us/articles/200168246-Understanding-Cloudflare-Development-Mode). To disable cache for a long time, can I activate development mode?
3 hours unless disabled beforehand.
in the support article you linked to and yes, it does only last 3hr.
To disable caching permanently or long-term, you can use page rule(s) and set Cache Level > Bypass.
Thank you so much!