"I just need an hour of your time to sit together to improve my slides. I know exactly what I want to say in tomorrow's presentation and all the slides are ready, they just need to be more visual"

I get this type of request often, and I usually turn it down. In one hour, 24 hours before the presentation, you can fix the layout of the slides a bit, but this is where it ends...

A proper presentation design process needs to go through a number of stages:

• The first briefing, what is the idea you are actually pitching
• Maybe in the same meeting, the more in depth questioning of the issues. The designer needs to ask the naive/ignorant questions
• Then putting the whole thing to rest, and scribble some ideas for potential slides over the next few days to come
• The creation of a basic graphical look and feel, usually I pick a "no brainer" slide for that, the content is crystal clear, it is just about style, fonts, colors layout.
• Then the drafting of the full deck, going back and forth between "no brainer" slides and the tricky ones.
• This draft gets then iterated back and forth
• Finally: rehearsing

It takes more than 1 hour, it needs more than 24 hours, it is not a polish of the existing presentation, which will have vanished totally in the process.

Image from Wikipedia