I don’t think they follow that anymore. I believe they ended. See Wiki...
Since 2003, blue slip policy has changed several more times, as follows:
“2003-2007: A return of a negative blue slip by one or both home-state Senators does not prevent the committee from moving forward with the nomination — provided that the Administration has engaged in pre-nomination consultation with both of the home-state Senators.”[4][5]
From 2007 to January 3, 2018: The chairman’s blue-slip policy allowed movement on a judicial nominee only if both home-state Senators returned positive blue slips to the committee. If one home-state Senator returned a negative blue slip, no further action would be taken on the nominee.[5]
January 3, 2018 - present: “The lack of two positive blue slips will not necessarily preclude a circuit-court nominee from receiving a hearing unless the White House failed to consult with home-state senators. Hearings are unlikely for district court nominees without two positive blue slips.”[6]
In October 2017, Senate Majority Leader Mitch McConnell announced that he believed blue slips should not prevent committee action on a nominee.[7] In November 2017, the Chairman of the Senate Judiciary Committee, Chuck Grassley, announced that the committee would hold hearings for David Stras and Kyle Duncan. Stras’ hearing was held up by Senator Al Franken’s refusal to return the blue slip, while Duncan’s hearing was held up by Senator John Neely Kennedy’s indecision on his blue slip. Kennedy, however, consented to Duncan receiving a hearing.[8][9]
In February 2019, attorney Eric Miller was confirmed to serve on the Ninth Circuit Court of Appeals, despite the fact that neither of his two home-state senators (Patty Murray and Maria Cantwell, both of Washington) had returned blue slips for him.[10] He was the first federal judicial nominee to be so confirmed without support from either of his home-state senators, although other nominees were similarly confirmed to the Courts of Appeals without blue slips later in 2019, including Paul Matey (Third Circuit, New Jersey), Joseph F. Bianco and Michael H. Park (both Second Circuit, New York), and Kenneth K. Lee, Daniel P. Collins, and Daniel Aaron Bress (all Ninth Circuit, California).
I understood that for district judges, they still followed the blue-slip protocol, which is why there are still many vacancies in states like NY and CA were the dem senators are stonewalling.
Also the judges that have been nominated in those states have been confirmed very easily with very few dem senators opposing (which means these aren’t conservative judges, but tolerable for the republicans)
Some of the judges were actually nominated by Obama originally but never confirmed before the session expired.
the blue-slips are not followed for the appellate courts anymore.