Yes there's no accurate way to set it up without T4 but if there's any loss of compression such as the valves not being lapped in properly then it's often impossible to get the adjustment down to what it should be
It was on the service schedule but generally it was never carried out, it's essential especially if the throttle body or head gasket have been replaced.
Whenever I see a 1.8 it's almost always out of adjustment and I normally adjust it to spec if possible.
Russ