I use to make it when the train into Gatwick Airport arrived earlier than its been timetabled to in recent yeses. Of course it helps with the train to Eastbourne is late.*cough* I've successfully made this extremely unofficial connection several times. But the argument being put forward is that Redhill is an adequate interchange for NDL passengers travelling south. It simply isn't.
The interchange at Redhill is only good if all you are doing is travelling on 1 other train from Redhill to a destination south of there. As soon as Gatwick Airport comes into play for interchange, things are not as good.
Th8s might be improved with the connection time between services from GWR and other operators was 5 minutes instead of 10. I believe it is 5 minutes for some operators or services unless I'm mistaken.