fan-out and fan-in does not matter much with todays CMOS designs because CMOS basically has a fan-out of >1000.

Just be careful when you attach a device that is not CMOS, you may be in trouble because you 'forgot' to check Iomin vs Iimax.

With CMOS the main concern is capacitive loading, if you do not pay attention you may end up with some nice round pulses.

Erik