Long story short, it tooks approximately 7 hours do dig a shallow pit with a digging stick and strength 5 or 6 (which suppose to correctly represent a miniature elegant and physically weak lady).
Both fireplace and shelter are requiring shallow pits, which are 1m in diameter, 0.30 m deep and 0.25 m3 in volume.
So…
First she (that elegant weak lady) should gathers 20 stone, which is already questionable, and then she digs the the heck out 1/4 m3 of dirt for 7 hours, thirsting, starving and freezing in the process, because somewhat smaller pit will never do the job of containing fire from a couple of sticks.
And then she should dig out another 1/4 m3 of dirt for 7 hours just to get some twigs above her head.
Does that seem right? I personally think not.
Even weakest person should be able to not be a freaking industrial excavator in order to survive.
Fireplace and shelter recipes should perhaps require just a digging tool and and a little bit of extra time instead of a huge freaking pit 1m in diameter.