There are 3 levels in presentation design understanding:
- Spotting that a presentation looks really good (99% of people can do this)
- Spotting that a presentation actually does not look good (this is still relatively easy, although a surprising number of people, including some who call themselves designers, are unable to do this)
- Creating something that looks good, this is the really hard bit
A bit of modesty here: I too find myself stuck in level 2 often with my own work, pulling my hair out why it just does not come out right. In the end it is usually good, but it takes effort.