There are advantages to training Loki in a huge field!
Loki seems happiest working sheep in the big 4 acre field.
When we first started him with sheep, various people felt that to train a small dog who cannot out sprint sheep (although he can just keep a pace with them) in a huge field was not a good move, as the could get away from him & he wouldn't be able to control them.
Our current training sheep are 'dog broke' but if you do the wrong thing they are OFF! Megan, partly because she is unwilling to go to their heads (which is actually where the control is) struggles to control them in the big field.
But Loki is doing pretty well in the big field, they seem to think he means business, & the size of the field means there is no danger of sheep panicking & running into a fence, which means that for the moment I am letting Loki get more confident by making decisions himself & developing his 'vallhund' instinct.
It also allows me to look at his style & study how he manages to get the sheep to cooperate, & how he actually keeps a really nice distance from the sheep on his 'fetch'...