How long can I sign a work visa for Myanmar in Ruili, Yunnan?

Burmese people can work in Ruili, Yunnan without a visa for 3 years. The longest service visa is three years. I want to renew it and sign it when it expires. The longest visa processing time is 3 working days (Myanmar time), and the fast tourist visa processing time is 24 hours. The processing time starts from submitting the application, completing the payment and receiving the application confirmation letter.