Whitaker’s run in the first year suffered from a crowded TARDIS crew. 3 companions never works as well as writers think it will.
Ideally it means 2 parallel stories of 2 pairs.
A story: Companion + Companion
B Story: Doctor + Companion
But usually one pair suffers from being underwritten or one Companion gets sidelined. So many fainting spells and twisted ankles. The Companion paired with the Doctor typically is superfluous.
Only a few times it worked were a few stories in Hartnell’s 2nd season (Vicki was far superior to Susan she replaced) and The Macra Terror under Troughton (one Companion was turned evil). It never worked with Davison.
