Timetable for event.
One simplification could be the following:

Create just one content type called presentation that has speaker, agenda, time, title, and company as fields (and anything else you want).

Then you create one view which lists nodes of type presentation.


In the fields portion, you select all the fields you think are relevant to show in the table, perhaps just title and speaker.  The title can be a link to the full content.
Perhaps have the style be 'grid' and order the items by 'time', so the ones in the same time slot are on the same row.


That's one idea to make it simpler.  Does it work in your case?