Unsure on the layout of this station in particular (whether tickets were checked for boarding that specific train only or multiple platforms). From my personal experience as a guard its quite common for me to do a full ticket check leaving say, Chester and find passengers who have bought a 1 stop ticket to Bache (£2.40) to get through the gates then boarded a service intending to travel 2 hours to Holyhead (£24+).
As mentioned above its also good for general security having a visible staff member, its nice to talk to people, ensuring people have correct railcards, checking people are actually on the right train (very common for people to get the wrong one it turns out, then a panic ehen they find they are going somewhere else!). I have checked somebodys ticket before then noticed them asleep after their destination, usually very appreciative of being woken up closer to their original stop rather than in 2 hours time!
I always ask people if they know where they're changing if applicable - which often results in questions such as what time is the connection, which platform etc. Even questions like is there a taxi rank at XYZ?
It's also good to get through the train and check in on people who require assistance, if you know there's a booked assist onboard just double check where they're going, any connections, what assistance they require etc and then it not only reassures them that they've not been forgotten but also I have the right info from them to call ahead to wherever they're going. Also encounter multiple people whilst doing a ticket check who don't require assistance as such but then ask some help getting their bags off at their destination.
I do a ticket check after a large barriered station as more of a check up rather than revenue protection, its good to know where people are going, answer questions and generally engage with people!
