Courier coverage in India is not uniform, and pretending otherwise is how a seller ends up apologising for something they could have predicted.
The three cases
Metro to metro. Fast, several couriers competing, usually two or three days. This is the case everybody plans for.
Metro to a small town. One or two couriers go there, and the last leg is often a franchise. Add days, and expect the tracking to go quiet before it moves.
Anywhere to a remote PIN code. Sometimes one courier. Sometimes none. Check before you promise, not after somebody has won the item.
What actually drives the variance
Distance matters less than you think. A well-connected town 1,200km away can be quicker than a badly-connected one 300km away.
The last leg is the whole problem. Trunk routes are reliable. The final delivery is a person on a two-wheeler who may or may not find your buyer's lane.
Festival weeks stop everything. Separate post, because it deserves one.
What to do about it
Test your three most common destinations before setting rates. Real quotes, real PIN codes.
Offer collection where posting is a bad idea — pickup turns "I cannot send this" into a sale.
Say what you know. A seller who tells a buyer in a remote PIN code that it will take ten days and it takes nine has a happy buyer. One who says three and takes nine has a dispute.
Questions people ask
Which courier is best?
There is no universal answer. Compare coverage to the places you actually send to, then claims process, then price.
What if no courier serves a buyer's PIN code?
They will tell you at booking. Offer collection, or cancel before dispatch rather than after.
Do I have to offer all-India delivery?
No. Zones exist precisely so you can say where you go.
Why is a light parcel expensive?
Volumetric weight. How rates work.
More: setting up delivery.