Bava Batra 28: Is Three Years Required to Establish Chazaka?

Today's daf discusses the presumptive ownership, chazaka, of properties.  The Mishna teaches that the chazaka of any property or fields which must be irrigated by people, is established from working them and possibly profiting from them for three years.  Non-irrigated fields (those dependent on rain, etc.) are not required to be worked every day for those three years.  Rabbi Yishmael says that the first three months and the last three months must be worked daily and the middle eighteen months are enough to establish a chazaka.  Rabbi Akiva says that only one month at the start and end plus twelve months in the middle are enough to establish a chazaka.  Rabbi Yishmael adds that this would hold only for white fields, fields of grain.  For fields of trees, certain work is equivalent to three years of work: gathering produce, harvesting olives and gathering figs.

The Gemara questions how these rules regarding chazaka compare with other rules of chazaka.  For example, in Ulla it was established that an ox must gore three times before it is warned.  Only after the fourth goring is the owner punished.  Does this suggest that land should not be officially possessed by a person using that land until four years of use?  Does it matter when the actual owner makes a claim to the land?  And if that person does not make a claim, should that action be taken by others in the community on his behalf?  In the case of a goring ox, the owner must be present when the claim is made - would that be true in this case, as well?

We then learn about how different crops are active at different times.  Certain flowers or trees might bloom for a number of days in a row, and one would only profit from their harvesting at that time.  Are those days considered to be one event?  Or, like an ox that gores, are they individual, distinct events?  

Our daf ends with an example of why three years and not three harvests establish chazaka.  Rav Yosef speaks of a purchase of a field where Jeremiah (32:44) was quoted to prove that writing a document of sale would prove ownership when a person could not utilize the property for the full three years.  Jeremiah recommended that people should write such documents in their tenth year for the eleventh year of ownership, when the land would be overrun.  It is suggested that this teaches us both to write bills of sale as good practice, and that chazaka may take place with fewer than three years utilized.

One point of particular interest is Rabbi Yishmael's assertions.  I had assumed that Rabbi Yishmael brought forward his points not because he believed that they were true, but because he was arguing any relevant perspective he could find.  The rabbis tell us that Rabbi Yishmael believed the perspective that he raised.  I wonder if this is always the case in the Talmud, or if rabbis sometimes raised points of view simply to hone other arguments.