No , it's not overkill. See this analysis for the output of Arcadia T5HO 12% tubes :
viewtopic.php?f=34&t=235611 ,
..... the aim is 180-200 microW UVB / sq.cm ,
No UV globe or tube designed specifically for reptiles produces as much UVA or UVB as bearded dragons are exposed to in their natural range for most of every day of their lives in the wild.
Ref to this :
viewtopic.php?f=6&t=234801&p=1806497#p1806497
If it were stilling ontop of A FINE mesh lid in a viv 18in tall , the UVB will be only about 50 microW / sq.cm on the floor = (1-M)xP(x=18in))= (1-.4)x80 = 0.6x80 = 48 microW UVB/sq.cm which is very low
and equivalent to early morning and late afternoon (within 1 hr of sunrise / set).
