There are some fascinating threads in this forum on the rights and the wrongs of established routines. I haven't been running long so can't really pass any opinions on these but I do know a bit about horseracing.
Very few horses require exactly the same programme to reach racing fitness. Some can be got fit with steady uphill canters. Some on a couple of gallops a week. Others - sometimes called 'gross', can take seriously punishing amounts of work, and might still need a couple of races to reach their peak.
The real skill of a racehorse trainer is finding out exactly the right routine for each horse - too little work and they run out of steam on the racecourse. Too much and they're over the top having 'left their race on the gallops'. There is also the talent of 'letting them down' after each race then building them up again again to maintain their fitness, soundness and mental enthusiasm for a full racing season. Many now swim as part of their schedule. I've known some which herded sheep on the hills and stayed fit (especially mentally) just on that.
One horse might relish working competitively with other horses while another will refuse to even trot if another horse is near him and must be worked alone.
I think there's a reasonable chance that humans are the same. While some general training rules might apply to all, each runner needs to find just what is right for him or her. And the mental aspect, especially keeping yourself 'sweet' on training, may well be as important as the physical. Happy running. (And neigh slacking!)