a lot of different parts that you have to carefully delineate and you also need to carefully pick what part are you predicting from what so that involves a lot of design choices to make type of parameters that you can only know by trial and error so that makes it really hard for you to use it on a domain or task that you don't really understand well and then you require multiple forward passes for these smaller versions of the inputs now and so that means that you be pre-training on something much smaller but potentially