Originally Posted by flying_geek

It is (pretty much) true for EXP. Whenever there is PE space available for upgrades (IE, they would sell upgrades) EXPs are entitled to get them for free.

1, There is no automated process to put EXPs on an upgrade list. So you have to ask. It is NOT necessarily a gate thing either. You can ask at check-in, and if there are upgrades available for sale - you will get one for free. Sometimes, if you haven't already upgraded a segment - you might get a prompt at OLCI, sometimes later.
Categorically - when there was space and I asked - I got a free upgrade.
2, Because it is a manual process, if there is no immediate space available for sale, things can go off track at the gate. The agent is supposed to upgrade if you asked, but may "forget" and "accidentally" clear employees into PE etc

People say they sometimes get free PE if an SWU failed - true - but has nothing to do with SWU - having the SWU replaces the "asking" part only. You can even ask at check-in, get your free PE upgrade and a SWU to J applied at the gate. There has to be space, and you have to ask.

I rather frequently buy MUC-CLT-FLL-CLT-MUC and pretty much always buy outbound in Y and return in J (discounted fare classes of course) - Not once when there was space in PE did I not get the upgrade (when asked) at check-in. Sometimes I get a free offer when checking in at the app.