Do 2 speeches in depth and have an essay prepared for them.
Make a paragraph for every other speech on a theme/common idea that links to either one of the two speeches you studied in depth.
Saves time and you can talk about 3 speeches in an essay if they specify one (unless the question is really narrow or they say you can only refer to 1 other speech which i think is a low chance).
The two that i did were Keating & Sadat and i was able to prepare a paragraph on every other speech somehow linking them to either Keating or Sadat's speech.