The LJN Tejas has a dynamic pricing, I think. Either case, it gets filled later than LJN Shatabdi and even Gomti Express [I mean, not that there is much overlap b/w 2S preferring pax and CC of Tejas preferring folks]. At the last moment, there are only 2 options for Lucknow to Delhi [if you discount 1A in Gomti which is perpetually empty]: Tejas and the not daily LJN-ANVT DD [but it has bad timings and is often delayed].