Another issue about backbone supernet pre-training

[Someone-LikeU]

Hi, i read the paper again, in section 4.3, it confuse me that how can you make sure that the best backbone architecture(path) can be sampled in the pre-training stage and the sampled path is different from the previous paths?
Since there are about 78 billion possible backbones(paths), and i think it's impossible to pre-train them all and maybe the actual best backbone(path) was not been sampled, so what if this situation was really happend during your expirement?
Thanks, looking for your reply.