I love writing army lists, which I can honestly say wasn't always the case. Previously, in my non-playing days, I would write out a basic list with a nice wide spread of units and work to that one list, which usually ended up around 4000 points.
As you can imagine, that didn't work so well for winning games, so I began writing lists to specific points levels.
Once I started winning games, I then began to want to play with different things, so I started writing lists around a theme. Some work better than others of course, and my 'default' selection I've discussed on this blog before, but it mainly consists of two bike squads, a tactical squad and centurions backed up by other elements.
Recently though I've noticed a major trend in my games with that list, which is that the tactical squad and their librarian support don't get into the game much. I think there are two main reasons for this - first is due to the different way 7th edition manages objectives. Because objectives are now placed before table halves or deployment type are determined, the tendency at my club has been for players to place objectives more in the centre of the table rather than in deployment zones, meaning units can't just camp on them from the start and being mobile is much more important. Added to this, the ability for any unit to now hold an objective means that if there are objectives in the deployment zone, there are better options than the medium range tactical squad to hold them.
The second reason is one of my own army composition, specifically that because I mainly use bikes and fast moving units (or drop pods), the majority of games result in the fight being much further up the table than if I had a more static force, with the tactical squad and librarian therefore being out of effective range much of the time.
With that in mind therefore I decided to make a change to my list, by replacing the tactical squad. That left me with another issue, of havin a footslogging librarian and only the centurions for him to join. That was never an option, as I'd be leaving way too many points out of reach on the table with little to do except buff the centurions with blessings.
What to replace them with though? The tac squad had a plasma gun and plasma cannon, so I was taking out some AP2 shooting against elite infantry and light vehicles that I'd need to replace somehow. Requirement number 1 though was that whatever I took would need to be able to keep up with the fight. I'll be honest, I thought about more bikes, but I really think two full squads is enough for now (I may revisit this later...).
In the end, after ruling out assault marines, another flyer etc, I re-read the codex for inspiration. My eyes settled on the landspeeder entry, knowing I had two unpainted in my garage, and I noticed something I hadn't registered before now - not only are they fast skimmers, allowing them to shoot two weapons even when moving 12", but they have the deep strike rule, meaning that equipping them with multi meltas could give me great tank busting capability, as my bike meltas often struggle to survive long enough to get within half range.
I had the seeds of an idea, multi meltas would give me a replacement for the plasma weaponry I'd lost, and for a secondary weapon the typhoon missile launcher would back that up with another 4 S8 missile shots, ideal for mass stripping of hull points. Two landspeeders equipped like this used up all the points from the tactical squad, so I had the Libby's cost to play with.
My only concern about deep striking the speeders was the potential inaccuracy might leave them out of half range for their alpha strike. The missiles would make up for this against light vehicles but for the heavier stuff I'd need that extra die. Step in some way of locking their deep strike on target then, and though the skyshield pad does this perfectly, it's easy to avoid. A locator beacon on the drop pod would also achieve this objective, but again can be evaded.
Finally I settled on a good, and very satisfyingly fluffy, choice - scout bikers. 4 of them with grenade launchers and a locator beacon could deploy after the enemy, secure accurate landing for the drop pod and still provide the same service to the land speeders. Even better that they fit so well with my army theme!
In conclusion therefore, I think it's important when you use a 'standard' list for your games that you constantly evaluate the performance of the units within it - don't judge any unit on just one game, but don't be afraid to change a winning list if some units are consistently not affecting the game.
When you do decide to change a list, try to work out why some units aren't performing as you'd expect and make the changes to take account of those reasons.
Oh yes, and if your changes don't work, apply the same logic - my landspeeders might miss with all their shots and get totalled the next turn, but I'll give them a few games grace to see how they perform over time against a variety if opponents before deciding to keep them in or cut them out.