There are different schools of thought on this issue. Some like to re-visit patterns, but I think most, once graduating to cold binds, do not advocate going back to the pattern field. Patterns are intended to teach momentum, holding a straight line on the initial send and use repetition to ingrain the sequence of cues for a blind. They are less about teaching factors and casting.j
In order to work on concepts, like cutting corners of water or cover, or multiple re-entries, I prefer to teach using Pop-up blinds or permanent taught (school) blinds. First I move up to place the factor or re-entry in the first third of the blind, rather than the middle or end. I teach it up close (since distance erodes control) then gradually back up once my dog is 85% or more successful at each stage. I try to find 3 to 5 school blinds in different locations that include the same concept. Once taught, I come back and run these same blinds cold once a week or so until the dog is lining each one. Then I start incorporating the concept into cold blinds keeping the factor in the 1st third of the blind and eventually moving it to the middle and end as my dog shows an understanding of the concept and has success.