I have one waterproof tool box that carries my most used tools. In that box are the mini makita drill and impact gun, charger and extra battery. They have to be the best thing yet...small yet enough balls on the impact to drive most any screw, and the drill will do up to 1300 rpm and up to 13/16 in wood.
But I typically take a minute, think about what I am going to need and bring that with me. Doing more with less saves time and money.
I bought the impact when it first came out, and I found myself a little wiery to bring it on job sites, other guys with the full size would make fun of it...untill they saw it work...now many of them have them...now I can't live with out it...