Ah, I never thought about that. I wrongly thought that the nRF24 if working as a receiver, is like my FM radio receiver, the strong the signal the better, because I can always use the volume knob to adjust any too strong signals received. Anyway, I need to pause a bit and google harder, to make sure I am not thinking other amateurish thoughts. On second thought, perhaps I can add a manual signal and volume adjust option to my python program. Cheers.

@StevenCellist About your comment: "... I did get a warning on my B+ model actually about one of the pins already being in use, but it continued anyway ...", I vaguely remember that one of the reasons that you might get this kind of warning messages is that you are trying to set a GPIO pin to input or output mode, but that GPIO pin has already been setup earlier. So it is just a warning, nothing important. There seems to be a flag to disable this kind of warning, but again not that important.

By the way, I found that I need to use a GPIO pin to control the CE, module enable/disable pin for certain kind of Tx operation. And we may need another GPIO pin set to input mode to entertain the Interrupt status output of the nRF24 module. So now I need two pins x 4 for 4 modules of my project. I think I need to write a simple python GPIO only module to handle these 8 CE/Interrupt pins.

Now I am going to assign GPIO pins for my 4 nRF24 modules. I looked at the pinout map and found there are not too many pins to go around, because the 6 SPI buses occupy quite a number of pins. So my first thought is to just use SPI1, SPI1, and forget SPI3 to SPI6. So I assign 1 GPIO pin for each module's CE, and one more pin in pull down configuration, to share among all 4 modules.

The pin map is rather messy, even I am only looking at the SPI pins. I still need to entertain the 5 I2C buses and at least one UART/serial TxD, RxD. Indeed I cannot make end make and must make a big engineering trade off in using the pins.

I always wrongly thought that SPI0 has CE0, CE1, but SPI1 has only CE2, but no CE1. Now I found made a mistake, there is actually CE0 for SPI1, but no CE0. I don't know why. Anyway, now I extracting the following pins/wires: SPI0 CE0, CE1 and SPI1 CE1, CE2. Together with Ground wire, each of SPI0, SPI1 has 6 wires, as show below.

Please let me know if you guess why there is no CE0 for SPI1. This seems inconsistent.