Yes, twice a day when the lambs are young. Once a day is okay later on, unless there is any other reason to see them twice.
Best time to check on families is dawn/very early morning - usually the ewes are curled up with their babes. Later on it gets harder to check mothering and even to count lambs, as the lambs play their own games!

If you feed cake, it's a good idea to check that the families have regrouped successfully afterwards. Lambies nearly always get a milk feed after mum's had her cake.
