Many more outcrosses result in birds from Group Two, and it often pays to retain a few of the better hens and pair them back into your own lines. It will usually be worthwhile if you chose your outcross well. This is often successful for a short time, but eventually nature catches up. The better birds usually fail to reproduce in reasonable numbers. Problems with missing flights and tails increase dramatically.
Body size decreases.
The show birds are difficult to get into show condition, and then hold it for a very short time. The life span of the birds decreases. Many years ago, Canary breeders trod the same path that we in the budgerigar fancy are on today. They saw the light, and now do not pair buff to buff. Very coarse-feathered birds should be paired to birds of a finer feather to produce the ideal show bird a large bird of intermediate feather.