Should Obama seat Merrick Garland?

[Silent3]

13. Perhaps Obama can test the "pro forma" pretense of the Senate...

...actually being "in session" all the time being abused to thwart recess appointments.

As for whether the Senate has "has waived their right to advise and consent", in this case I don't think it's just the time period that comes into play. There has been an explicit declaration that the Senate will not even start the process necessary for advice and consent.

And as for the time period, I don't think there's any concern that treating many months of intentional neglect as a waiver would lead to treating 24 hours as a waiver. While the Constitution doesn't provide a specific time period, in the absence of such the courts are certainly free to decide what time period and circumstances are or are not "reasonable" for delay.

I think getting a favorable ruling from a majority of the current eight justices would be pretty good. Garland would, I suspect, have to recuse himself from taking part in this ruling.