I know that when a 3rd tone is followed by another 3rd tone, (3-3) it is pronounced (2-3). On the other hand, I know that a 3rd tone followed by a non-3rd tone and on many other occasions is pronounced a "half 3-rd tone". For example (lao3 shi1) is pronounced (lao3h shi1), that is (3h-1)
My question is, Is it correct to pronounce a (3-3) as (3h- 3h) or it must be pronounced (2-3) anyway?