Well , the fact is that governments of developing countries are quite corrupt ,and they will not want to do the right thing at the right time.
However ,presently once a retiree met up to the requirements for receiving pension , he is paid within two months of retirement , especially when the person retire in a government section. The only challenge is that ,for states with low internal generated revenue , the payment may not be consistent. The pensioners may be owed some months pension at some point ,which can still be paid later.
My mum retired February 2020 ,and after submitting the necessary documents , she started receiving her pension after two months , and so far she still receives it up till now. The only one that she is yet to receive is gratuity.
Nevertheless , yes there some people that will have to suffer for years before they are paid pension ,and this is quite unethical