I am having a long time discussion with a buddy about the no deco time shown in a computer. How close can you get to the zero time while diving, without risking too much. Some opinions are to go up when you reach the 10 min mark, some consider the 5 minute mark.
That depends on your definition of "too much".
The point at which you reach NDL=0 depends on (1) what gas you are breathing, (2) your depth and time (profile), (3) the algorithm that your computer uses, and (4) any adjustments that you have made to that algorithm to increase or decrease conservatism.
For pretty much any modern algorithm, the risk of decompression sickness if you ascend at the calculated No Deco Limit (NDL=0) is acceptably small. Meaning that it's very unlikely, but not impossible to get bent. And there are many other factors that increase or decrease your risk of ascending at NDL=0 (e.g. fitness, hydration status, areas of previous injury, vascular anatomy, water temperature, activity level, etc...). So even if you got someone to make up a percentage chance of DCS for Algorithm X, profile Y, and conservatism settings Z, that number still wouldn't be accurate since no computer knows if you have a PFO or if you are hung over or if you are a 25 year old Navy Seal.
If you have the option for multi level diving, you will see that NDL number grow again when you ascend. Certainly, ascending at NDL 10 would involve less decompression stress than ascending at NDL 0, all other things being equal. But all other things aren't equal, and that difference in decompression stress might not be clinically significant.
Hedging your bets by padding things a bit if you are diving a lot is not a bad idea, as mentioned above. Just remember that no matter what the magic bracelet tells you, DCS is a risk of breathing compressed gas under water.