The most obvious one is that if you're shifting between tenses - like if you're doing a flashback or even just stuff like a character walking down a street and reminiscing a bit - a lot of people don't know how to do that as smoothly in present as in past.
Re: X or Y
The most obvious one is that if you're shifting between tenses - like if you're doing a flashback or even just stuff like a character walking down a street and reminiscing a bit - a lot of people don't know how to do that as smoothly in present as in past.