So in 4-player Bang!, there is a Sheriff (wins when all others are dead), a Renegade (wins when all others are dead) and 2 Outlaws (win when the Sheriff is dead). So your typical game opens with the two outlaws shooting the Sheriff, the Sheriff shooting the Outlaws, and the Renegade being forced to shoot the Outlaws so that they don't kill the Sheriff too quickly. This has the effect of telegraphing to all players involved who the Renegade is; the resulting game devolves into a shootout with no subtlety or strategy; everyone knows everyone's situation and there are no surprises. Are there better or more optimized strategies for these situations? Or does the game only hit its stride with more players involved?
Well in a 4 player game there is no real incentive for anyone to hide.
The Sheriff can kill anyone since the worse case is killing the renegade first who is at best is only a temporary team mate. Anyway you look at it they will need to kill all other players anyway. But if the sheriff knows who the renegade is they might just ignore them to focus on the outlaws so that they have a little more help.
Both outlaws just need to focus on the Sheriff as there is no real incentive to kill the renegade since it takes away from damage they can be doing to the sheriff. Now if they can't do anything to the sheriff then it might make more sense for them to work on the renegade.
As for the renegade you need to deal with the fact that both outlaws will be wanting to kill the sheriff and the sheriff will probably want to focus on killing the outlaws first as there is more incentive to kill them first (3 cards and they only have the goal to kill the sheriff). If the renegade can come out early and get the sheriff to focus on the outlaws then it is easier to build up some strength while killing both outlaws and leaving the sheriff in a weakened state.
Honestly I think its in the best interest of both the renegade and the sheriff for the renegade to play a little more on the deputy side then they would in a bigger game as it can help the sheriff survive both outlaws.
There is still a bit of strategy to be had. If the Sheriff is clearly getting the upper hand, then try shooting him instead of the outlaws for a while. Plus, it can add in a bit more distrust into who is an outlaw, which can cause them to shoot each other.
Also, the outlaws might want to kill the Renegade, because there will be one less person to be attacking.
Still, if you know who the Renegade is, in general, you should ignore him until the end of the game, so it doesn't really matter if he's caught.
I'm not sure Bang! is really about maintaining cover, anyway. Even for big games, it seems like ideal Bang! strategy is...
1) Outlaws try to spike down the Sheriff roughly ASAP, though they can sometimes wait until most players have long-range guns before exposing themselves.
2) Once the Outlaws are dead, the Renegade immediately tries to kill the weakened Sheriff before he gets time to recover.
The only subtlety I see is that, if the Outlaws are having a tough time, the Renegade should stop shooting them.
You're right, though, that in 4-player, because the range is so short, Outlaws don't even need to wait until long-range guns are out. And there's no moment of wondering who the Renegade is -- in larger games, that moment is brief, but it does exist.