Hi I'm not sure if this will help, or whether it's still an open thread being from 2014 but someone might read this like me lol, I think the store-bought suet cakes are dense I think they use more flour or cornmeal or whatever ingredient they use, it's denser (it's harder, more compact) than the texture of lard type homemade suet cakes and once the weather starts getting colder near freezing point they become too hard for the birds beaks to pick at and feed on, and if you try to push your thumbnail into a nearly frozen shop bought suet cake in winter temps it's like a brick, the lower temps make suet harder, making it impossible for birds to eat them or hard to even push your fingernail into them (you could possibly grate them with a cheese grater to use them up or grind them to crumbs or crumble them down with a mallet. So I stick to my homemade lard cakes for very low winter temps and in spring when the temps start to rise I use shop-bought ones for summer and my homemade lard-type cakes that still are soft enough for the birds to peck into and eat when the store ones are too hard for the birds to eat