In the past couple of days, the reward from completing daily focus has been largely underwhelming. It has just been a lot of potions and one or two commons.
I'm seeing a lot of people complaining about the rewards lately and I'm experiencing the same. I don't know what is happening but I think Splinterlands might have changed the drop rates.
To maximize the daily focus points you have to try to use the cards from the specific challenge you're trying to farm. For example: When you have a flying daily focus every monster with the flying you use will give you a bonus in the number of reward points you get from winning the battle.
My advice would be to focus on winning, if the challenge fits the match then go ahead and use some of the cards for a little boost otherwise ignore the daily focus and go for the win.