I think the world would be a little bit better if Talend had a copy function for tHashInput which allows to copy the schema from the linked tHashOutput. In design time as a one-timer, of course. That would save a lot of time if one had to fill 20 tables or so (which I had to). :-)
You can still copy the schema from one component and paste it in another component. Or if you have fixed schema to be used across objects, you can always define it in Metadata and use the repository schema objects.