I've always been under the impression that the older bucks move around quite a bit, so including them in your management plan is only purposeful if you have a significant amount of land, or if you see and ID them individually quite frequently (indicating territoriality). The yearlings represent 60% of my cull target, 30% are older beasts, with 10% being in the middle aged category (at least,,,,that's the goal!)...The first step of course, is to identify of what number these ratios should come from. On one peice of land I have, I estimate around 100 deer population, this is the number I see as suitable for the size of the land, and which the farmer is happy with too. So I set up to cull 30% pa, of which:
a. 18 are yearlings
b. 9 are older deer
c. 3 are middle aged
I will always take those which look ill or injured first, then move on to those that are weaker, and finally those that are just available to cull..Now that's my 'ideal' plan, but rarely does it work out - but it gives me something to work towards at least.
If I estimate 30 bucks on my grounds, the yearling cull will be 5-6 (ie. 30% of 30 is 9, of which 60% (5-6) are yearlings). Then I will look for 1 middle aged buck that's either not in too great shape, etc. The 3 older bucks will be taken based on my luck and the size of the trophy - these guys are my 'thank you's' to myself, except if there's an ill animal, they will take priority of course.
I will repeat the same exercise with the does.
Eventually, I hope to end up with a doe to buck ratio and a spread age demographic which is healthy, sustainable, and which I (and the farmer) is/are pleased with.
There's no doubt that if you want to have a good number of trophy bucks, you can't have a bunch of marauding yearling bucks running around the place,.that might mean the older buck is on your neighbours ground, and have thrown them away to your grounds.
My belief is also that when syndicates can work against proper deer management and actually do worse for tree plantations! ie. syndicate members tend to travel a bit to get stalking (I'm not trying to generalise, so please don't take offense), and will prefer to take bucks (the bigger the better) to does, and might not get together very frequently to set and review cull plans, take deer counts, etc. etc. etc. Therefore what you can see is an increasing doe population eating the top shoots, as well as an increasing yearling/young buck population (bad for fraying), as the older trophy bucks are shot off, and are no longer around to kick the young yearling bucks off their territories.
IMHO, deer management has got to be done right and taken with a degree of a scientifc approach, but for smaller grounds such as say below 500 acres, there's hardly a point, so management should be more about ensuring you don't cull too much of the doe/buck population, and to cull any animals that are ill and injured - in these cases, take a 'general' approach, and don't waste time being to scientific. from 1000 acreas up, I think you can start thinking in terms of numbers for deer population purposes...again, just my opinions based on reading and my experiences...but I'm no pro, nor an old gamekeeper, so take my thoughts for their face value, not wisdom