I think that there needs to be a combination of both, especially during difficult periods such as this.
If it was a case of a young, progressive team not getting the results that their performances deserved, I'd be in favour of giving them as much time as possible. We're not seeing anything close to that, though.
Short-term thinking is problematic when you put the likes of Bolasie, Schneiderlin and, to a lesser extent, Sigurdsson on upwards of £80k a week for four or five years. Getting a few lads in who can put their foot on the ball for half a season is virtually zero risk.