Ok, here's your answer. While OLCI does not officially negate any opportunities for subsequent upgrades, in most situations it will. Why? For starters Hilton's own OnQ front desk training teaches that you shouldn't mess with a reservation where someone has checked in and chosen a room. Why would you? The guest chose THAT room. Meaning if you check into your reservation where a one category room upgrade was already done, don't expect the desk agent(s) working that day to give you another upgrade in advance. Why would they? It's more work for them and it goes against what your trained not to do unless there is an extenuating circumstance.

Writerguyfl's comments are basically spot on with the idea that it's an employee by employee decision. I work at a property where there are only five desk employees and we all handle upgrades differently. Two of the five (GM included in the two) basically won't upgrade anyone, ever, and the rest of us do it situationally based on whether we want to or not. Sure there are properties out there with upgrade policies in place that tell their staffs what they should/shouldn't be doing but overall it's basically each person/shift doing whatever they want.