In a math talk (at a seminar or a conference, not teaching) that uses projected slides, is it better to display the number of slides left or not? What are the pros and cons? Some people tell me they like it, others prefer when it doesn't appear. I'd like to have some objective comments about this.
For some context, talks in math are typically one hour long, so the number of slides can be large. I like to cut talks into a few short sections. Right now I'm using the following layout, displayed at the top of every slide (from the "Frankfurt" beamer theme):
The current slide in the current section is highlighted, as well as the title of the current section.
A method to please both probably exists. Just tug a #/## at the lower corner, with the first number being the current slide number and the second one being the total slide number. People who have question on a certain slide can jot down the number quickly and come back (rather than "Can you go back to the third dot under 'The Model?'"); people who find a large bar intrusive will be less likely bothered by some small numbers at the corner.
I personally don't have problem with how beamer displays the time-line; it looks elegant. (I sometimes use it just to be that "lone kid in the department who uses LaTeX.") However, it requires some skills to be truly effective. Too many times I have seen very long section names used in this device, which clutter up the time-line badly.
And to be honest, I'd rather save the area on the slide to arrange information beautifully for those who pay attention then to give up 10-20% to set up a device for those who doze off and want to hop back in. Even I do care about them, major section signposts do not need to be on the screen all the time, the speaker (or a transition slide, or a small phrase next to the #/## index) can also deliver the transition.
Disclaimer: I don't give math talks, I work in biomedical field.