Would say however you please in one young bird section this year i have 3 x 10 Pipos on back wall and 2 sets on side wall.
Other section at the minute has 24 Widowhood hen boxes but once they are gone it will be a mix of V perches, box perches and anything else i can find in the garden
my stock section at the minute has 6 proper boxes, 3 old widowhood hen boxes, block of 3 old rabbit hutches and 2 walkers boxes - will let you guess which they took first.