You can’t underestimate how the death of a parent brings latent hostilities within siblings. Could go on for days with stories of how siblings you thought were all for one, one for all, let’s just do this right are quarreling over minor details, asking for extras, wanting to submit claims, angrily they should get this or that.
Wills preclude a lot of this. If the parent makes clear what is going to happen, there’s a defense against a lot of things. Please be prepared. There’s no substitute for getting your affairs in order.