I am not a professional, but if the bees draw out good from foundation, while a good flow is on let them have at it. For plastic, I found out some suppliers put more wax on than others. The bees will be really slow to get started if there isn't enough wax on. I have heard/read that some beekeepers will make swarms to get comb drawn.
I have noticed when I hive a swarm, they do seem to get the job done in a hurry.
I am going to try to go back to all wax foundation in my brood. then when I get ready to change out I don't have to worry about the plastic cleanup. The plastic is good if you are extracting honey, it doesn't blow out like wax foundation with the extractor I am using. Till I can get the other one.
doak