How many times a week I wet my hair depends on how I am wearing it. I'm a two strand twist gal a large percentage of the time. When it's time to cleanse and condition my hair for the week, I do a myriad of things to infuse my LP strands with moisture (i.e. overnight prepoo/overnight DC, moisturizing low 'poo, RO, LI, FSG and final step a very light coating of my oil mix to seal. Since my strands are LP, I don't need a lot of oil for sealing purposes.
If I go on to put my hair in two strands after my weekly cleanse and conditioning, then I don't need to wet my hair again until I wash and condition again which for me is every 5 to 7 days. If I wear my hair out like in twist out for instance, I do wet it very lightly every day until I wash and condition again. The effects of all the moisturizing don't last as long when my hair is not in twists. The twists themselves lock in moisture. When my hair is out, I lose the moisture locking feature and it can dry out quickly thus become brittle and dry and start to break.
My son's hair is about 5 to 6 inches long and he wears it in a 'fro most of the time. Sometimes I put it in flat twists. He wets his hair everyday when he wears his 'fro and his hair stays moisturized for drama and pain free pick out sessions when he styles it.