It really depends on the type of network you have. You can share the internet connection via a router, and share the printer out via one machine whilst mapping the other computers to the shared printer.
.... and what i guess the types of router also depends upon the number of systems to be connected all together and the same is true for the speed and efficiency demanded out of the utilizing network through a router
No to 25 yes to 20.
According to Microsoft's License Terms.....
Device connections. You may allow up to 20 other devices to access the software installed on the licensed computer for the purpose of using file services, print services, Internet information services, and Internet connection sharing and telephony services on the licensed computer.
I believe you can have as many as 20 concurrent connections for the purpose of file and printer sharing but I would not expect it to be particularly robust compared to the same situation when linking to a "Server" You may experience some problematic behavior like disconnected mapped network drives and or disappearing network shares, but I would certainly be interested in your results if you attempt to use one particular Windows 8 desktop as a "Server" in a 25 machine workgroup.