Great point about the flexibility GILT funds offer to the individual
on when exactly one wishes to book income/profit, 
(compared to GSECs requiring planning while investing in them, and accepting periodic income)
Yes, in one line, that’s it.
For the past 5 years, it has been several crores of INR available on BSE/NSE on a daily basis.
However, at any exact moment on any given day,
which of the numerous GSECs is going to be liquid is anyone’s guess.
Here’s a snapshot at one specific instant of time (presumably in SEP 2023).
[ Source: Investment in Government Securities - #22 by viswaram - MadeForTrade ]
At any given point of time,
there are ~100 outstanding GSECs with varying maturity, yield, and liquidity. 
Add SDLs, T-Bills, and STRIPS into the mix (investments with extremely similar counterparty-risk),
and the number of scrips to monitor explodes to ~1500.
With slightly different attributes/properties between each of these classes.
IMHO, a key challenge is the lack of an intuitive user-interface around such sovereign bonds.
Some brokers provide better user interface to manage this complexity, others don’t.
Here are a few examples of what is possible, but missing -
a. Quickly filtering and listing all GSECs, sorted by yield based on current ASK-price in NSE/BSE is supported by some brokers. giving the user the ability to pick a GSEC suited to their needs (returns, maturity, liquidity).
b. Being able to place a limit-order that is active for a month, along the lines of -
“Purchase upto INR 1Lac of any GSEC, SDL that offers an effective yield >9%, maturing between 3 and 10 years”
Am not aware of any broker that is focusing on providing an intuitive terminal for all of this.
However, with real-time market data API access, and a little bit of imagination/coding,
one can easily create custom terminals for this purpose for ourself.
(How do i know? I have built a couple such terminals for “personal use”.)