One key feature of Patriarchal Period.
This is a biblical period from the time of Abraham to his great grandchildren sons of Jacob. It has different geographical location starting from Ur of Mesopotamia to the land of Egypt.
At this period, a male was the head of the family or clan and could make a decision which was followed (with few exceptions but also in those, he had to give consent).
Supporting examples
We can see what happened to Abraham. He had settled well in Haran after leaving Ur of Mesopotamia, a richly built city and one day (in obedience to voice of unknown God to others), decided he had to move to unknown destination. The household just followed for the head had said. (Gen 12:1-4)
We look at where patriarch was to consent. Sarah, Abraham’s wife despised Hagar, her househelp she had given to Abraham to bear a child, and wanted to humble her put of the house and family if possible. She only did so when Abraham, the head of family consented.( Gen16:6)
Importance
Knowledge of the common practise among communities during patriarchal period, will help to understand why they did some activities.
In example of Sarah offering a maid to her husband was to solve the issue of barreness. It was not extraordinary circumstance. It was commonly done.
This may not necessarily mean it is right for our practice for patriarch Abraham did it as well his grandson Jacob.