Malaysia, like many other SE
Asian countries, has quite a large population and in the case of Malaysia, it is spread over three specific areas - Malaya, Sabah and Sarawak.
Malaya makes up most of the Malay peninsula and twelve of the Federation's fourteen states, while both Sabah and Sarawak (the other two) share the island of Borneo with Indonesia and Brunei.
Malaysian (MAS) flies to nine destinations on the Malay peninsula and islands, eight on Sabah and fifteen on Sarawak. Many of the domestic routes are plied by 734 (the workhorse for the area) and indeed quite a few by A333 and occasionally 744's.
Examples of routes using 734's are KL
to Kuching (1hr45min), Kota Kinabalu (2hr35min), Langkawi (55min), Penang (50min), Kota Bharu (55min) and Johore Bahru (45min) among others. All of these destinations have over half a dozen flights a day with 734's.
As you can see, some are quite lengthy (direct/non-stop) flights with quite a demand for frequncy.