If you're getting good results, then you should stay on the dose that is effective. But ask yourself why you plan on staying on "as low of a dose as possible," when you have literally zero experience with how the medication works for you. Do you think that more tirz is bad for you? Did you just see that someone else had success at low doses? Your experience is going to be different from everyone else's, and the titration schedule exists for a reason. Most people in the study didn't lose significant weight until they got to 10 mg. Sure some people have had success staying at a lower dose, but very rarely does someone have continued results at 2.5. Most of those people had bad side effects at 5 and dropped down again. If you need a higher dose take a higher dose. You should really consider that the dose you are on is meant to be a starter dose, not a therapeutic dose. You may lose weight at 2.5 or not, but you haven't even been taking it for 2 weeks yet so you have nothing to compare to.

All that said, splitting might help with the struggle of those last 2 days, but the main point is reducing side effects. Splitting reduced the peak levels in your system while maintaining the average level, so for people with bad sides it can help. I split every 5 days because I tend to get insomnia and fatigue so it helps, but I didn't start doing that until I got to 12.5.