Hmm.. okay if you say so.Who said that it's just a Viggen rip off, it's probably the only product in the world that has been impregnated by every major source in the world.
As for the period, we'll it's no secret that this sad tale is running some 30 years late.
Proof of how successful a weapons development programme (especially the fitst generation) has been, can be seen, not by how much time it took to develop a weapons.
But what new technologies have you imbibed in developing that weapon and how you can build on those to develop next generation of weapons.
While Tejas might have taken time. It gave Indian scientists techniques and expertise on how to develop an aircraft from scratch.
That is why India's 5gen AMCA is well on its way, where as Pakistan's 5 gen Project AZM is already done and dusted, before it even began.