+0
In the following sentence, should it be effort or efforts . . .

Competition has heightened with the development of a regional open heart program, declining market volumes, and area cardiology groups’ continued effort to develop additional office-based revenue streams.
+0
Either one works, but because 'groups' is plural, 'efforts' might be better. Basically, it depends on whether the writer is thinking about many individual efforts of different sorts, or of a general effort to solve the problem.

'It will take much effort to solve global warming.'
'It is the many little efforts of each citizen that makes a country great.'
Comments  

It should be efforts.Because the sentence is talking about continued attempts.