I think a better strategy would be to take doses closer together. It also depends on which brand of tabs you're taking. I use Hammer Endurolytes and as far as dosing, I typically take 2-3 before the start of the swim and then 3 or more per hour, depending on heat during the rest of the race. The best rule of thumb for any nutrition is even portioning. You don't ever really want to go a long time without any aspect of your nutrition, water, carbs, electrolytes, etc. You don't want to put yourself into deficit then try to remedy the problem by dumping a lot of something in. Keep the levels constant, take tabs every 20-30 mins, thats my reccomendation.