So why tell people that three repairs for the same item will result in a replacement?
Because this is Apple's policy. To the OP, I
do recommend you try, if you think you have a valid case.
The repairs need to happen within a reasonable amount of time for the replacement to be even considered, and they don't need to be for the same repair.
Unless you are calling the warranty period "a reasonable amount of time," you are wrong.
The issue could first be reported on the 31st day of ownership, and the third be reported on the 1095th, Apple wouldn't need to evaluate the timeframe. The CRU must be authorized by someone above level 1 in CS. Unless there are some extenuating circumstances (like yours, for instance). The main difference between you and the OP being that it sounds like you had repairs.
A software issue (that isn't caused by faulty hardware) is 99% of the time the fault of the user. Apple helped the OP resolve the problem, but they aren't admitting fault, nor are they going to see those incidents as relating to the stability of the machine. Also, he has a 2008 MBP that has been replaced for the faulty 8600 GPU, which is an incredibly common for that model.
I have repaired about 50 of those machines, replacing the LB under the Quality Program, and not had a single one come back for another repair. The replacement units are not of the same design as the faulty units. It is possible that the OP got another bad LB with a faulty GPU.
It has been plagued with numerous hardware and OS-related software problems over the years, including currently having its logic board replaced for the SECOND time around due to the failure of the GPU.
Since Apple won't recognize the "software problems" as flaws in the computer, we can scratch those, right off the bat.
It has also had its optical drive replaced due to failure.
A very common failure in Apple computers.
The computer has also had numerous minor issues, which apple has carefully avoided dealing with after I informed them at the time of the first logic board replacement (such as premature wearing out of the keyboard and trackpad and flickering issues with the screen).
Though these issue would often be solved by LB replacement, Apple doesn't ignore customer complaints. Since nothing was replaced, we can only assume that Apple found no fault with the hardware.
I have AppleCare. Do you think this is enough ammo to glean out of apple a new MBP? I understand that they typically only replace after the 4th major repair?
So his tally of problems recognized by Apple is this:
2 - Logic Board (one replaced with a known defect).
1 - ODD
Since one of the LB replacements was due to the 8600 known fault, I think the chances of Apple giving him a new computer for one LB replacement and one ODD replacement are slim. However, if OP throws a big fit on the phone with them, there is a possibility he will get what he wants. You are better off having a broken computer when you are making your case, but he might get lucky.