But there's no maintainence scheduled at New Delhi, even if it arrives late the returning train can be departed on time, but it got rescheduled quite frequently atleast some months ago.
The main problem is it's never able to arrive at destination on time on both sides EVER. Better to slow it down to maintain some punctuality and not cause inconvenience to people.
Same should happen with Allahabad Lokmanya Tilak Terminus AC Duronto too, it's never able to arrive LTT on time, even if it arrives 20 minutes late at Allahabad sometimes due...
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to slack.

These days Railways doesn't care about class of trains- Ahmedabad Duronto extended to Rajkot with stoppage at Surendranagar and Howrah Duronto diverted via Jasidih due to Dubeyji.
You should also consider the mass slowdown of trains in Southern Railways which included prestigious Shatabdi trains too.
As much as I hate myself while saying this but I think it's about time for some slowdown of these trains, for their own good.
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years ago I never thought I'd say this.😔😔

Yes i agree this train has a serious punctuality issue never arrives destination on time....even ER does not give priority to this train from ASN to SDAH stretch.....gets delayed in this section also....ER has too much of mail/sf/premium trains but most of the trains have a very slow and worst TT and punctuality except the rajdhanis most are slow TT. I have earlier wriitten to RB to stop some of these slow TT loss making trains in the busy hwh to dli and even asn -pnbe route this will lessen the congestion in this route...some trains that block the route and create congestion i see is
Sdah-varanasi upper india
Sdah...
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-dli exp
Kol-pnbe exp(earlier used to run till dli merging lalquila &janta exp now short terminated till pnbe)
Hwh -asr exp - needs speed up with few halt removal
Doon exp-needs speed up
Bagh exp- needs speed up
Udyan abha toofan exp
Koaa-jat exp needs speed up removong few halts
And many more to name. These trains has very slow TT creating congestion . These trains either needs speed up to remove congestion and railway can stop few of them or short terminated them....because of few such trains some hood trains like yuva exp,duronto exp both sdah and hwh, himgiri, etc gets late everyday.