Manual of course no problem. Because you are in control of the gear @ your current speed. So when you cruise and its time to speed up you just put it in whichever gear appropriate.

But in auto/cvt, you shift to N and cruise then go back to D, the transmission can get damaged cause the car is already moving at speed while engaging the gear. Same thing also when moving from D to R/P, it is adviced to completely stop the car before engaging to a different gear.