I think with lurchers ,the way they run while young,all legs etc will tell you if they are ready for the odd run ,they need the muscle that goes with their structure ,no need to wrap in cotton wool but ensure they are ready physically,and to a degree mentally,
It's all about keeping them winning and finishing on a high.
Most of the time they WILL do more than they are ready for that's immaturity on their part,but as they do more make sure you build their fitness and confidence at the same rate.then 1s and 2s then go home.
That's the hardest part knowing when to say enough.especially being