Martin, thanks for the comment! Could you explain a little more why do you need to specify ID for each layer?
Julian Ferreiro Of course! The main problem is that: If you have more than one PSD file to import into 1 template, the layers all start with ID 1 after you import them. The second thing it would make easier is that: Since we have an existing option set already, and would like to just change the position of the layers 200+ we need to set each layer their own matching ID and it's very tedious work to not make mistakes. So therefore if we have more than one PSD file to make it clean and easier for our designer and set ID's for layers from every imported file you can see it way better and make less mistakes. Rather than setting 200+ layers their own ID's in one-go from one imported PSD file. Would also like to add one more thing to this. If you import more PSD files into 1 template it arranges the layers unusually, not in order but for example 1 layer goes on top 2 layers go in the middle, and some on bottom. You might want to look into that as well.
Good idea! When we create option sets we like to increment ids by 1000 so that there is always room to add more options between existing ones without regenerating the option set again.