It's an awesome train when it comes to covering it's lost time after Kanpur Central. After the Rajdhanis/Durontos, it's a good train to travel to Delhi/Ghaziabad/Kanpur.
Actually, I gave this tip on the basis of my personal experience on this train way back in Oct, 2011. Now this train may have become a bit impunctual as train traffic is increasing by the time :-p
I remember, in my childhood days HWH Kalka Mail used to run with 16 coaches (end of 1980s and early 90s). It was real superfast. With the passage of time and introduction of new trains it has lost its charm and importance. I last travelled by 12312 in 2012 October from DLI to HWH and it was more than 5 hours late.
Yes ... it's route is now being ruled by Rajdhanis & Durontos. Even Poorva Exp needs to struggle en route :-p
Well, As on DLI-HWH Route Rajdhanis And Durontos Are given a high priority plus this route suffers from massive traffic,
So Mail/Express train Having Route similar to Raj/Dur Crawls even WB Skr and Poorva Exp Also Crawls on this route
(WB Skr is a better option Instead of Poorva/kalka)
the main area where it gets late is between CNB and MGS. The train is kept stranded before ALD and also before MGS. This can go upto 30-35 mins