Responsive Carousel Query

[lpug]

I'm trying to create a website by reducing the amount of breakpoints, so far its working well with just one default sze of 1920px.
I have a carousel slider within a flexgrid, the slides are set as cover. All works well on larger screen sizes, however on smaller screens such as 768 and below the sliders take up way to much screen size, I can create another breakpoint at 768 and then readjust the flexgrid and it appears to work as intended.
My question, is this the most effective way to do it? I dont want to get ahead of myself (like I normally do) in projects and then end up starting all over.

Why would you use a flexgrid over a layout grid or visa versa?

Thanks