I suppose I can only speak for myself and my own children.
I've not a done a scientific study on this topic.
I only have observations.
Children who seem to "bounce back" from difficulty often seem to be the happier children. The happy kids are likely those kids whose parents or guardians give them doses of love and care each day.
The children who seem to fall apart at a challenge often seem to be the children easily wounded by criticism. They may have a parent figure or leader at home who chastises them for every mistake, in the hopes of encouraging them to do better.
I think the adults who admonish, ridicule or express exasperation frequently are not leading or teaching their children how to survive disappointments. I believe that is their intent to do. I think they may have good intentions of "showing kids how to be tough".
"Tough" kids, resilient kids appear to be those who know that if they fall, someone will be there to dust them off.
I am not equating "helicopter parent" with this idea. That's a whole different thing. It's the parent or guardian who picks up the fallen, band-aids the cuts, kisses the bruise, laughs at the mistake, and says, "Oh, well. Next time." That's not a helicopter. That's a family. That's a support system. That's the belief that those who have fallen down can get up again.
"Next time" is so important. It tells children that this mistake was only a moment. It's not forever. There's another chance. There's another opportunity coming.
So, you want your kid to be "tough"? To be resilient? I think you should love them deeply, often and publicly. Ignore those "mature" adults who balk at your actions and call you a "helicopter" parent, say that you are "babying" them. I think they may not have had enough love in their own childhood to understand that children need love and support to grow up into loving and supporting people.
Look at the animals at the local shelter. Look at the fiercely angry or cowering animals.
They were thrown out, abandoned in times of difficulty, left without a support system.
Did that experience toughen them? Did they become more "resilient"? No. They became angry, suspicious or weak and fearful. Some may even have become dangerous. This is very similar to human beings. Some of those wounded pets still seek attention, affection. This is also similar to human beings.
We had a feral cat who hissed at us and threatened our pets. My husband began feeding it. Over time, the hissing reduced. Then it began to try to rub against our legs in a typical cat-love way. It had received attention. It had received care, food. It became less angry and less threatening. This, too, is similar to humans.
Resiliency is born in the confidence that misery is temporary and joy is always within reach. That is something which is taught; it is not innate.