Alfie has had four cages over his lifetime (he's 18 next month). Only one of them developed a defect (one of the bars came loose and I was worried he could pull it about and injure himself on it).
His original cage (the one that developed the fault) was replaced by a corner cage, because I moved him from my bedroom to the dining room in my parents house and the corner cage fitted the space better. I kept the original cage though and used that again when I moved out, as it fitted the space in my rented house better. Alfie also prefers horizontal space to vertical space, so the original cage was better suited to that as well. When my housemates moved out and I had the whole house to play with I upgraded him to the biggest cage I could find... which was also when the cage bar on his original cage became a problem anyway. I then bought my own house and he's still in that big cage now. Recently I bought him another cage (not quite as big as his regular cage) so that he can join me upstairs when I work from home. This will also be his 'holiday home' if he ever needs to stay at my parents house or elsewhere.