This tweet says it all:

Yes conference organisers want to 1) ensure that the presentations they offer are decent, 2) make sure the workflow of decks one after the other works on the conference desktop, but... most speakers will make changes to slides (especially the slide order) when they are rehearsing for the performance.

Suggested strategy:

• Ask for a rough draft, outline, or old presentation well in advance of the conference to eliminate potential issues in terms of presentation style and technicalities (fonts, etc.)
• Create a very credible deadline shortly before the conference for the actual slides.

Cover image by Curtis MacNewton on Unsplash