Carrying out a sunnah action without making the intention

Q: An act that's sunnah. When one started it, it was done with the niyyah of sunnah. After years you become accustomed to it, it becomes a habit like dusting the bed or reading certain duaas or eating with the right hand, etc. Will you still get the thawaab of practicing a sunnnah or will the niyyah be have to made every time you do an action? Some aalima said that one won't get rewarded without the intention.

Making an intention to gift half of one's property

Q: Muhammad owns a property. He was thinking of giving his wife half ownership of the property and may have made an intention in his heart to gift it. He never told her verbally directly or indirectly about this and as far as she is concerned it belongs to him. Neither did he tell anybody else or wrote anything about it.

He later decided against giving it. Does he still own the full property or does his wife now own half?