Nick
If you want to foster a positive working relationship with the regular TS judges at tribunal venues then I would say it’s vital for a PO to attend every case.
We always send a PO no matter what the case and this has been met with praise from judges (and chairs previously). Conversely, DWP who at one time did not regularly send a PO came in for some criticism.
Luckily our tribunal venue is based in the city so we haven’t got any issues with travelling there and back. You may take a different view if you are based miles away from the venue.
We are currently finding though that unless the appellant is asking for an oral hearing, regardless of our stating a PO will attend on the AT37, hearings are going ahead on the papers. We’ve not experienced any problems with this as all the cases have gone in our favour.