Why did miss Marsh's uncle not leave her everything in his first will why did he allow her the use of his estate for one year?

Miss Marsh's uncle may have had reservations about leaving her his entire estate due to concerns about her financial management skills, her ability to handle the responsibility, or to ensure that she was ready for such a large inheritance. Allowing her the use of the estate for one year could have been a way for him to test her readiness and capability before entrusting her with everything permanently in his final will.