In the United States, elite upgrades are very hit or miss in general. As someone mentioned upthread, I think the main factor is how a property is managed. If the property is good about elite benefits than OLCI vs. check in at the front desk should have little to no impact on what room you receive. E.g. properties with good elite recognition are pre-assigning rooms for upgrades regardless of if you have already checked in via OLCI.

On the other hand, I have seen properties that don't appear to be good at elite recognition also handle OLCI poorly. They just assign the first available room very early in the morning regardless of my stated expected arrival time. Not only are the rooms not an upgrade, they may not meet my standard preferences (e.g. high floor, away from elevator). Since my typical arrival time is late afternoon or early evening, the property actually had plenty of time to wait an assign a room later that met my preferences and still be ready for my expected arrival.

Distilling it down, for properties I stay at frequently, who also hopefully have good elite recognition, I will typically use OLCI to save some time upon my arrival. For properties I stay at infrequently (or one and done properties for road trips), I will probably still do OLCI to save time. Especially for one night stays, I don't care that much about upgrades. If I wind up staying at a property frequently that is good at elite recognition but poor at handling OLCI, I will go back to check in at the desk.

There are really only two types of stays where I really care about upgrades. For business trips of 3 or more nights, it is nice to have the extra space. If it is a suburban or roadside stay, I will frequently just book a FI Suite or a larger RI room for a minimal price difference from the basic room to guarantee the extra space. For city stays, where I am likely to be at a full service property, I will choose properties that tend to be good with Elite recognition. Most of the time at these properties I don't even have to ask for an upgrade. The upgrade may vary based on how busy the hotel is that week and some weeks they may not be able to upgrade me at all. It is all part of the game but I know they are truly trying to upgrade me.

The second type of stay I care about upgrades is with my family. I use SNA's when available for these stays. Success rate with them has been reasonable but not prefect. For peak summer beach stays and similar, I will typically book an RI where the standard suite is fine. I have never had success with upgrades for these summer beach stays and just accept it. I have still had very nice reward stays at the beach that saved my family a lot of money. If a property offers a better room for more points, I may go for it. Depends on the uplift. We have discovered over the years that we don't tend to use the really nice in room views even when we have them. So not really worth it to us to spend a lot of points on them. More space (suite or otherwise), we definitely use an appreciate. YMMV...

--Jon