Why? Some components may get really hot and you may need to place there heatsink or find another way how to take the heat away, otherwise your board may not work properly.
Altium has a lot of free templates for different form factors. For example, if you need to design a PCIE card, you don’t have to create it from scratch. You can download it and it will save you a lot of time. Here is the link to the Altium design content website: http://designcontent.live.altium.com/