I need more help in late afternoon can I take 1/2 a pill phentermine in am other 1/2 pm? Will it be?

Hey, my sister is on phentermine and she's played around with when she takes her pill. Because of her schedule she takes her first half around 8.30am, after her breakfast as she has to have a late lunch and then her second half around 2.30pm, after her lunch. She says this works great for her as then she doesn't get the mid-morning and mid-afternoon cravings like before. Because of the stimulating effects you might have trouble sleeping if you take one in the afternoon, so I would try with half and half and see, if you're still having trouble then take one maybe early afternoon like between 12 and 1.