Firstly, Not all the pins on the 40 pin header are GPIO pins. Some are power supplies like 3.3v, 5V and GND. Generally speaking these pins can be shared by many devices and can be "split" to go to multiple devices. Just need to bear in mind that there is limit to the amount of current you can draw from each supply.
As for the real GPIO pins, it depends on their function. The I2C and SPI pins will allow connection to multiple devices (providing the other devices support this). With all other pins, you need to be more careful to ensure that they aren't shared by multiple devices and if they are, whether this will cause a problem.
Your e-ink and LCD devices may for example both use the SPI pins, if they do, then you need to ensure that whilst they will share MISO, MOSI and SCLK pins, that they have separate CS (Chip select) lines otherwise both devices will listen at the same time.
With I2C devices, devices will share the same pins, but each device has a I2C address. The address needs to be different for each device. Some I2C devices have fixed addresses whilst others will be configurable, either via software or by changing some pins/jumpers.
is an excellent resource for checking for pin conflicts with commonly used Pi accessories.