Bottom line: The study at hand confirms that the assumption that more helps more rarely applies, when the thing you could take / have / ingest more of are dietary supplements. Rather than taking more, you should thus make sure to get the timing right - 2.5h before the workout(!), that's when you want to take your nitrate supplements or drink your beet root juice.
In this context, it's worth mentioning that timing, as well as the speed of absorption (see info box to the right) are probably less important, if you are looking for the recently confirmed beneficial effects of nitrite, as well as dietary nitrate, on arterial aging and prevention of age-associated CVD in humans (Sindler. 2014), I discussed in the info-box "Nitrates for your heart".