Do the injections buy time or just move the problem?

Had a shoulder that had been grumbling for months and a cortisone injection in February, which worked better than I expected - nearly four months of normal training. It is coming back now and I am trying to work out whether another one is sensible or whether I am just postponing the thing that actually needs fixing. For anyone who has gone down this road, how many did you have, and at what point did you decide to stop and deal with the cause?