Another factor in past-versus-present layout decisions would be that with mechanical signalling, quite often every switch needed a separate lever (and another for each facing point lock). This adds cost and size to the interlocking, and increases the workload (and time) for a signaller operating a 'ladder' junction versus one with fixed diamonds.
Power signalling allows multiple switches to be moved and locked simultaneously, so that's doubtless one factor in the popularity of ladder junctions these days.