She'll regret not doing dumbbell strength training when her back muscles no longer sustain her rack well.
(The busty women in my family would attest).
If your muscles aren't burning like you've been thrown into acid, it's not working.
It's hard to get low motivation people to progressively overload to this extent.
You can still improve with minor/medium muscle pain or even pain that dissipates after an hour.
But the gains are of course substantially less.
That said, such will lull them into it, they'll improve enough to gain the confidence to get more into it.
But do more than 0.7 bent rows lol.