The size (and even the existence) of an air receiver is absolutely application dependent. In some applications, it is better to have a very small or no receiver than to have a big receiver. In other applications a big receiver is mandatory.
Share some details and people here might be able to help guide you to an appropriate air receiver.
I had an application once that needed to slowly ramp pressure from the low setpoint to the high setpoint. Working with the compressor manufacturer and several control valve manufacturers we all determined that the best way to do it was to not have an air receiver and let the compressor build pressure to match increasing resistance--worked great, and the control's solution with a receiver was going to require a PLC and a bunch of custom programming. I admit that this was a really odd situation that hasn't been repeated in 30 years, but it was a real requirement.
Engineers need to keep an open mind for simple solutions that step outside the box a bit.
Think about how much variation you can accept in your system's air pressure when deciding on an accumulator rather than just going with a 'rule of thumb'. The rule of thumb may be adequate for your system or it could be oversized or undersized. An oversized accumulator may just cost you money but an undersized accumulator may prevent your air system from operating as required.
