Don't think Demon Slayer Marks were used against people who were equal to the characters. Akaza/Kokushibo/Muzan were arrogantly toying around for much of their fights. Muichiro was utterly overpowered by Gyokko and was trapped in his Water Prison Pot, but the Demon Slayer Mark gave him a sudden power up allowing him to escape the water prison and toy with Gyokko while holding back and affected by poison.
Tanjiro was below Daki when she wasn't at full power during their fight to the point that she could blitz him if she wanted (he only overpowering her temporarily when he burned his life force but he ran out of fuel before he can cut her head), and Daki is not noteworthy for Tengen.
While there is some reactive power levels going on, Tanjiro is still portrayed to be far below Gyutaro, as he was repeatedly being saved by Tengen, and Gyutaro compared Tanjiro to a snail around the end of the fight. Tanjiro's main method to help is trying to hit the homing blood projectiles from the side to change their trajectory away from Tengen, knowing that if he tries to face them directly they'll go through his sword.
The x100 boost is explicitly only for Tanjiro's case as it comes with a statement about a single strike not being enough and mustering a hundred times of that strength. It was not applied to every instance the Mark is awakened, in which case the Mark would have diminishing returns and be used for upscaling in future appearances.