I don't have any scientific studies to back me up and am not making any statements about what I think other people should do, but I can recount what I've decided to do and why, so it can possibly help other people in their decision process. I've actually put this info on some other threads, but thought I'd put it here as well. I'm primarily a gecko keeper and that includes mostly nocturnal geckos but also two day geckos. The nocturnal geckos are all maintained on calcium and D3 (Repashy calcium plus). They are fed 3 times a week and their feeders are dusted every other feeding. The day geckos are also maintained on calcium and D3 without UVB as per the practice of Leann and Greg Christenson (based on their book "Day Geckos in Captivity"). The day geckos are 8 and 9 years old and doing well. The only reptiles I have that are being provided with UVB lighting (bulbs changed every 6 months) are my two bearded dragons who are diurnal and fairly large. They get some D3 with dusted feeders twice a week.
Until recently, I was keeping my trio of RETF on calcium and D3 alone, dusting their crickets every other feeding. I've had them for 6 months and they seem to be doing OK. This past week I added a 13 watt UVB compact florescent to the frog enclosure which I plan to replace every month. I also have a LED light for the plants. I decided to do this for several reasons:
--the frogs sleep often in the open. My nocturnal geckos mostly sleep inside their hides and wouldn't benefit from UVB during the day
--the day geckos eat fruit nectar in addition to the crickets. The nectar is formulated with calcium and D3 and is considered a complete meal for them
--I have no idea how long it takes the frogs to eat the crickets. I've never seen any of my frogs actually eat a cricket, but the frogs appear healthy, there is plenty of frog poop and there aren't too many crickets in there. It may be that the crickets groom the supplement off themselves before the frogs can eat them. That was probably the deciding factor to my adding the UVB light.

I have no idea how this will all work out; these are my first frogs. So far, things have gone OK. I'm grateful.

Aliza