I would like to point out something else --

The concept that a proper level of "normal work" in daily life is relative and arbitrary. In a rich household, they might consider making their own coffee "slave labor". In the olden days, people had to work hard for everything. Cooking meals was a full time job, with butchering, preparing, cooking from scratch, grinding, mixing, post-meal clean up, you name it. Today we have it SO easy.

If you're used to doing 2 hours of chores a day, that will be your normal.
If you're used to doing 2 MINUTES of chores, THAT will be your normal, and everything above that will FEEL LIKE hard slavery.

Which one would prepare a girl better for a future career as a housewife and mother?

Perception is reality, to a certain degree. Not objectively speaking, but TO THE PERSON what you feel or perceive IS your reality.

Yes you don't want to break them, but you want to raise them with a reasonable standard of working hard, so they don't end up lazy.

I agree with you, generally, on points 1 and 2.  It's not the siblings responsibility to raise their younger siblings.  But...it is their responsibility to help out the family.  It can be a fine line.

Points 3 and 4 are connected, in that, you relate stories where siblings didn't want to have children after their family situations.  I would say this is God's will, because raising children isn't easy and for a teenager to realize this isn't their life's calling, at such a young age, is a blessing.  On the other hand, some of this "trauma" might be temporary and the desire to have children may return later, once the young adult is able to move out of the house, and have some independence.

There's also plenty of opposite cases, (which is the more common situation in Trad families, in my experience), that older siblings become very good with children, and this prepares them for their vocation of marriage.

This ^^^

I understand and agree with the OP that parents shouldn't put all of their responsibilities off on their children and completely walk away and constantly leave their children in charge without a good reason. 

However, I don't think most traditional Catholic parents would feel comfortable being so hands off...

And if a parent wasn't taking charge of their children and put another child in charge I think that he should accept the responsibility out of obedience and respect towards his parents.

However, I don't think most traditional Catholic parents would feel comfortable being so hands off...

 Some of the worst examples of parental failure to supervise their own children I have witnessed happened at traditional Catholic gatherings.  Our group was almost kicked off the property because of the unruly children running around.

If one doesn’t go overboard in expectations of the eldest children, it can be such a wonderful training ground for adult life, especially for girls.

My eldest is 7 and she delights in helping to take care of her younger sisters. We are expecting a baby in April and she is just chomping at the bit to change diapers, rock for naps and to help with anything baby related.

I realize that some mothers are very burdened with a large amount of children and the outward appearance of joy is hard to come by, especially if their husband is rarely around or if they are having to chip in to make money for the family, or if her husband has died or is disabled. But aside from that, I think mothers need to take special care to serve their families with joy, to sacrifice ourselves happily and to be a good role model for our children. If a mother loves her role as homemaker and goes about it cheerfully, girls will want to be like their mom and will enjoy doing what she does. If a mother feels constant drudgery, a child will see that burden upon their mother whom they love and conclude that the care of children is a negative burden. Therefore, even if it is hard, even if we mothers are tired and a bit discouraged, we should give it to our Lord, gain strength in his good and holy will, and move forward cheerfully. What wonderful future wives and mothers she will produce!

Some of the worst examples of parental failure to supervise their own children I have witnessed happened at traditional Catholic gatherings.  Our group was almost kicked off the property because of the unruly children running around.

That is terrible!  😣

If one doesn’t go overboard in expectations of the eldest children, it can be such a wonderful training ground for adult life, especially for girls.

My eldest is 7 and she delights in helping to take care of her younger sisters. We are expecting a baby in April and she is just chomping at the bit to change diapers, rock for naps and to help with anything baby related.

I realize that some mothers are very burdened with a large amount of children and the outward appearance of joy is hard to come by, especially if their husband is rarely around or if they are having to chip in to make money for the family, or if her husband has died or is disabled. But aside from that, I think mothers need to take special care to serve their families with joy, to sacrifice ourselves happily and to be a good role model for our children. If a mother loves her role as homemaker and goes about it cheerfully, girls will want to be like their mom and will enjoy doing what she does. If a mother feels constant drudgery, a child will see that burden upon their mother whom they love and conclude that the care of children is a negative burden. Therefore, even if it is hard, even if we mothers are tired and a bit discouraged, we should give it to our Lord, gain strength in his good and holy will, and move forward cheerfully. What wonderful future wives and mothers she will produce!

Well said!  I definitely need to work on being more cheerful when I am overwhelmed with the children and duties of keeping house.  😅