Individual Timings for Google Slides
The File > Publish to the web… feature lets you add automatic advance for a set number of seconds to a slideshow, but that applies to every slide regardless of content.
For slides that need more time for the audience to view, you can add a text box like the one at the upper right, which has a non-breaking space in it, to a particular slide. (You can later set its border color to Transparent to make it invisible.)
Add the box to a slide, select it, and then:
5 second delay with visible box
This slide is set to display for 5 seconds by fading in the box at upper right.
You can see this by clicking the PRESENT button
and then hitting the PLAY icon at lower right.
10 second delay with visible box
This slide is set to display for 10 seconds by fading in the box at upper right for 5 seconds twice.
5 second delay with invisible box
This slide is set to display for 10 seconds by fading in the now-invisible box at upper right for 5 seconds twice.
10 second delay with invisible box
This slide is set to display for 10 seconds by fading in the now-invisible box at upper right for 5 seconds twice.
5 second delay with invisible box
This slide is set to display for 5 seconds by fading in the still-invisible box at upper right for 5 seconds. The box fill color and its border color are both set to Transparent so that even if the background changes it remains invisible.