Heavy cover for convoys threatened by Tirpitz

Did British battleships always patrol in pairs while covering against Tirpitz?

No. Heavy cover was concentrated around important convoys and could involve a single battleship when that was the force available.

British battleships were not attached to every operation conducted under the threat of Tirpitz. Heavy units were concentrated when large convoys made a German sortie particularly dangerous or likely. The later engagement with Scharnhorst by a single British battleship shows that the covering force did not have to operate as a permanent pair. The allocation was risk-based, balancing scarce capital ships against the periods when an Arctic convoy most needed a counter to German heavy units.