Most of the feeds being consumed by ruminants do lack certain minerals especially those that are fed solely on grasses. It is therefore necessary that they are supplied these minerals through salt lick.
Which one is better to use as salt lick: iodized salt or compact mineralized salt lick? The truth of the matter is that most compact mineralized salt lick contains more than sodium and chlorine (sodium chloride) whereas it is only sodium chloride that is contained in iodized salt.
So in my own opinion, I will prefer the use of mineralized salt lick for them. In fact it is less cumbersome to use mineralized salt lick than iodized salt. It can be placed in their feeding trough from where they can be able to lick it.
With regards to how often the salt lick should be used for the animals, as good as the salt lick is for the animals, it is not expected to be administered daily to the animals. I do recommend once a week for those using iodized salt whereas for those using solid mineralized salt, daily licking is okay for them as the quantity licked at a time cannot be too much for them.