The digital key still needs to be issued by the front desk though? So if you only do it after arriving you might have to wait longer than the people in line.
Unless it's different in the US? In the UK (only country I have used digital key) it usually takes 30-60 minutes to get the key after submitting olci, at least if ormal check in time has passed
We have some Hilton employees in this community who will likely chime in. My understanding is the digital key is issued automatically provided all the right criteria are met on the reservation (room is ready and it's a valid check-in time, valid form of payment, any ID requirements, etc.). As a practical matter as a US citizen, this means that when I am staying at a property in the US, the digital key shows up almost immediately upon request, or sometime around check-in time if I do it earlier in the day. If outside the US, local regulations typically require the front desk to validate an identity document (i.e., passport) which is done during check in. After that process I've typically had no issues requesting the digital key and having it show up immediately.
As for me personally, there are a few scenarios where I do digital key check-in and skip the front desk. The most common use case is some variation of when I am arriving late at night, often to an airport hotel, don't particularly care about an upgrade, and don't want to be stuck waiting in line. The other is if I see (or am assigned) a room that I like and just want to lock it in and be done with it. The only time I've ever been walked from a hotel was at a Hilton some years ago where I was one of the last guests arriving for the night. Another guest had some issue with their room so they took my room and gave it to them. I had seen the room assignment in the app hours earlier, didn't accept it at that time, but then it disappeared. Had I accepted the check-in at that point and been given the digital key, they wouldn't have been able to do that.