I've seen it a few times Chris and of course you cannot account for every single race.
I don't object to this though as it's the same for all, the parties involved know this beforehand and it certainly seems a better option in a Northern to have a heat and final on the same day than have them on Day 1 and Day 2 with the overnight stay that will often then be involved for some.
I object more to the mixed messages that come out of UKA and this is of that type - OK in a Champs to run 2 x 1500m, but in a Mid Lancs Track and Field League a U13/U15 athlete can't do a 800 & 1500.
Strictly speaking these rules allow a 10 year old to attend a Northern U15s 1500m Champs and run 2 x 1500m races within 3 hours of each other.