Bud already posted a good answer for the Tsunade part conserning Shikamaru. So I'll add my new 2 cents for the part on Sasuke.


No Mission is worth letting Sasuke go?
This is why the Uchiha were so arrogant. They treated them as the best of the best on Konoha.

Would you, as a leader show weakness to your enemies (risking a new invasion) or your allies (showing them a weak front), just to save ONE shinobi, despite his bloodline?

Think it this way. You cancel all your missions so you can retrieve ONE PROBLEM Shinobi... what will happen?

All your clients will say: "What? They cancel my mission before completing it? Screw them, Im hiring Iwa-nin/Kiri-nin/Sand-nin/Grass-nin/Oto-nin next time.

All your enemies will think: "Look. They are desperate to recover a Nin, the Sound/Sand invasion must have weakened them a lot, lets get them now.

One Bloodline, despite how powerful, and how much your enemy wants it, is not worth the destruction (physically or finacially) of the whole Konohagakure.

Will you risk losing the whole Hyugas, Inuzukas, Naras, Akimimichis, etc etc etc for a single shinobi? Ironically I mentioned the four clans that had a member searching for Sasuke.

No sir... Sasuke was not worth losing whole clans or the whole village. So they just sent to retrieve him whatever was available.