People can choose whatever skills they wish to choose, this guide is a foundation for people to start from, I have explained the skills and why and have expressed that this setup is for an overall performance, not 1-2 camps every 5-10 maps, if you want to skill your general for one map, then re-skill them again for another map, feel free, it's your game and your generals to do as you wish, but I made this guide based on my own findings and my own experiences with not only "currently" in mind but for the long haul so I wouldn't have the need to re-skill the gens on a continuous basis or even a periodical basis.
If a block is so tight that you need to gimp your general to complete the block, then my suggestion would be either find a way to kill that camp cheaply or find a way to block it longer, there are more than one way to accomplish a task in a map and if you try to just focus on one camp or one general and expect to have overall successful results, you will fail. like saving your pennies, 1 penny is nothing, but continuously saving them with the future in mind can add up to millions, if you skill your gens for damage, then that block you are so focused on might very easily be taken out with lower losses and then opens the door for more sacs and/or a different general to kill the boss camp which in turn reduces the losses even more.
You haven't tried out the other way to say that CL is a better option since you haven't actually tested both ways, just like you can't say that your block ACTUALLY saved you any troops since you haven't tested out any other ways. Giants in VLT for example is best killed with Anslem for the lowest possible losses, now he can't be used if you are trying to block the camp in front of it because he takes too long to kill, so sending Anslem to that camp in front with 100r and 50Cans, kills that camp with low losses, then you can configure your attack on the giants however you wish using Anslem and reduces your losses.
I was just using that one boss and camp as an example to show that there are other ways of thinking and planning to best utilize generals (in a general manner), but I have posted my skill tree suggestion and explained reasonings behind the arrangement I have set up, people can use my suggestion for their own uses or use a variation of them or use their own entirely, it's entirely up to you and them.