Yes always. Actually if you listen carefully enough you would find out that the u in Sakura is not very strong. It's a light tune you don't read it as Sakoora. Itadakimasu sounds actually like itadakimas. it's the light tune so bit confusing . I'm also studying Japanese on my own can I add you ?

U sound in Japanese is between u and i

I suppose you are talking about the pronunciation of U yea ? As far as I think, U has its own sound and it's between u and i For example Desu sounds like Des So ..does it make sense ?