It really depends on exactly what compact
UVB light you have, and what the wattage is. Most compact UVB bulbs are not adequate wattage for bearded dragons, including the Reptisun 10.0 compact
UVB bulb, which is only 13 watts, and even the Reptisun 10.0 T8 UVB tube if it's on top of any type of mesh lid and not within 6-8" of the main basking spot. Unless you're using a compact
UVB bulb that is at least 26 watts, it's really playing with fire, especially if on top of mesh...I've not heard good things about the Arcadia compact UVB bulbs at all, their 12% and 14% tubes are fantastic, but just like the Reptisun 10.0 compacts, they just don't emit strong enough
UVB light for a bearded dragon.
As far as Calcium, you actually should be using both with and without vitamin D3, even with a very strong UVB tube like the Arcadia 12% or the Reptisun 10.0 T5HO, you just don't need to use the D3 as often. I have been using nothing but 18", 24", and 36" Reptisun 10.0 T5HO UVB tubes for the past decade for 4 beardies, one being a rescue with severe MBD and partial paralysis of his back legs, and #1 Their age determines how many times a week total I dust with anything, and then #2 the
UVB light being used determines how often per week I use Calcium with D3. Using a strong, efficient UVB tube such as the Arcadia 12% or the Reptisun 10.0 T5HO is obviously your best bet, as supplements and even food are not replacements for adequate UVB exposure for beardies. You cannot guage how much calcium and/or D3 they are really ingesting by dusting, nor how much they will actually absorb. For my babies up to 8 mo the I dust their live insects every single day with Calcium, and 5 times a week with a multivitamin. I use Calcium with D3 3 times a week, and without D3 4 times a week. For 8 months (sometimes I won't change until they are a year or older, as with the rescue with MBD) and older I dust with Calcium 5 times a week and multivitamins 3 times a week, and I use D3 2 times a week and without D3 3 times a week.
If I was using a compact
UVB bulb that was not at least 26 watts (which most aren't, again the Arcadia compacts do not get good reviews, though I don't know the wattage, the Reptisun 10.0 compact is only 13 watts, half the necessary UVB or half the wattage of the 10.0 T5HO), and the beardie was under a year old, and I couldn't get his basking spot within 3-4" of the compact
UVB bulb unobstructed (by mesh) I'd probably be dusting with D3 every day.
It's that big a deal. But again, I don't know what the wattage of the Arcadia compact
UVB bulb you're using, that is going to make the decision for you, well, and how it is mounted and at what distance it is from his basking spot. My recommendation is to switch to the Arcadia 12% tube, that's the best way to ensure he's getting proper UVB, UVA, and can get his vitamin D3 naturally, by making it himself, which is the best way.