I use both TS% and EFG%. When I update the numbers every few games depending on my free time.
The numbers don't really start carrying weight though until you have a sufficiently high number of attempts for that player across 2pt, 3pt, and FT. That point can happen at different times of the season depending on the player's usage, the teams tempo, etc. Generally, I don't put much value in the numbers until the player has 100+ points. I also balance it against what I would expect a player of that caliber to produce based upon his ratings. The numbers get more accurate as the season goes on and the sample size gets bigger. There is a argument to be made, however, that even at the end of the season, the sample size is too small and the variation in opposing talent from game to game too large to ever have an accurate number, but I tend to think they provide decent value. On my best teams, I tend to schedule in the top 20 SoS and try to play pretty consistent levels of talent so the numbers have more value because the quality of defender is pretty consistent game to game.
Although I understand the point about FTs, it seems the more my players drive, the more offensive fouls they commit which offsets some of the benefits of drawing fouls on the opposing team.