I find alot of people will say salted is better or frozen, from my personal experiences I find it depends on the fish that day. There have been days where they only take the salted and on other days the same species will only take the frozen.
My usual ritual is that if I do not have salted pillies at home waiting to be used, or I'm low on them, I will buy a block of frozen pillies. At the end of the session I will have a fair bit left over.
For those left over Ill salted them for future fishing. As their thawing, Ill collect the liquid and take the pillies that appear to be mangled then chop them up and place into the liquid to freeze (this is after thawing complete and before salting - PS, salted liquids does not turn into ice). The pillies that make it through is then salted for 24hrs. You can keep salted pillies outside but must make sure its its enclosed and in the shade at all times but I left mine in the fridge.
End result, I have salted pillies on standby and a couple of burley bombs. Also I have made a slow release burley bomb. Basically a cut down PVC pipe with holes in it. Also use another piece of PVC pipe to make the cast to throw the liquid into before freezing.
I believe everyone has their own way of doing it but all agree that is is far cheaper and have control when you do this yourself. I might consider some of the above methods to give a go as never thought of doing it in that way before.