In this sugya we focus on the parameters of Z'man Tefilah. The well-known Mishnayos in Brachos detail the specific z'manim when one must begin davening, and when the time expires. However, there remains the question amongst the poskim regarding the correct behavior if one calculates that he won't finish Shemoneh Esreh until after the zman.

In such a situation, should one assume that he has missed the zman, and therefore make up the Tefillah by davening the next Tefillah twice instead?  Or, should he perhaps say Hevinainu (an abridged version of Shemone Esreh) so that he can complete his Tefillah in time for the zman?  What if Chazaras Hashatz will be said after the z'man? May the Shatz continue the regular Tefillah, or should he say a "Hoiche Kedusha" instead?

This sugya ties in to Parshas Balak, where there is a discussion regarding Bilam utilizing his knowledge of z'manim when determining the best time to curse Klal Yisroel. Tosfos in several places says that once Bilam started his curses, he was able to continue even though the opportune time had expired. Some Poskim discuss whether the same applies to Tefilah as well.