Depends greatly upon which bullet he plans to shoot!
The 131gr Blackjack Ace requires a 1:7.5 twist.
Ditto the new 133gr Berger Elite Hunter & 135gr Berger Hybrid Target bullets.
Cutting Edge requires a 1:8 for their monolithic 115gr MTH bullet.
The 131 Blackjack does not REQUIRE 1:7.5. Neither do the two Bergers. With a 25-06 or larger, Blackjack themselves recommend going with a 1:7.75” to 1:8”. Why? RPM. Really high RPMs contribute to poor accuracy and risk of midair blowups. FURTHERMORE, if one chooses to go with a 7.5”-8” twist, he must also accept that he is significantly limiting which bullets will work well when he is not shooting heavy bullets. Really heavy bullets drop velocity, and that reduces RPMs, and heavy bullets require fast twists, BUT when you do that, you have to understand that shooting light-mid weight bullets will result is more velocity, and more RPMs and many lightweight and mid-weight bullets cannot tolerate those RPMs. Many will, but you must be mindful that there a lot of bullets out there that will not reach a 100yd target from a 1:7.5 twist 25-06.
On a side note, the Blackjack is standing up to higher velocities than Berger Hunting line. That requires thicker jackets. The Berger target line uses thicker jackets to insulate enough to prevent it from melting and slipping at high RPM. Berger’s balistic gel testing indicated that the thicker jacket of the Target line did not yield consistent results the way the thinner jacket did. I don’t see any ballistic gel tests from Blackjack, and I don’t know if their jackets are thicker or thinner than the Berger target line. I only know that jacket thickness is the key to withstanding high RPMs, and the Blackjack must be thicker than the Berger. I would say that if you intend to use the Blackjack on game, at least find as many reviews as possible before doing so. Lots of hunting bullets use very thick jackets BUT all of those use very nose designs than open tip target bullets do. Too thick of a jacket in an open tip match bullet can result in the bullet behaving more like an FMJ, which is generally not what you want when hunting.
If I was looking for a serious edge in long range competition, I would look very hard a 131 BlackJack in a 25x47L or 25CM with a 1:7” to 1:8” twist. Going with the extreme velocity of a 25-06, I would lean much more toward a 1:8 to 1:8.5, particularly if I knew I would not be shooting at low altitude, and even more particularly if I had an interest in shooting any other bullet through that rifle. The two new Bergers do not need as much twist as the 131 Blackjack and should work better in a 1:8” to 1:8.5”, but they have lower form factors. I’m not suggesting that they are better bullets, BUT I would suggest that you could build a gun to shoot them and have a gun that worked slightly better with light to medium bullets.