Relatively longer to satisfy necessary CTI, but should not exceed the time as per damage curve of protected device. Consequently, if there are too many, it will be impractical to achieve coordination. But as to the limit, I haven't read any standard and you can install as many as you want but could be impractical at some point.
Right now its about 6 units but varies upon contingencies. The number is so high because this is a recloser loop scheme. Basically the feeder is broken up into 250 to 1000 customer chunks. Every segment has a normally closed source recloser and a alternate tie recloser.
That's interesting. Anyway, if ever you encounter a coordination problem, I think you can consider using sectionalizers depending on the intended application.