its all depends on ranks,S on bard in silver is whole different story in gold,and its not much in plat and diamond.
s in silver is not a indicator,its doesnt mean that its working,atleast if ur goal is higher rank.
I told what to do and what to focus if u climbing is ur goal.
U will see by urself how ur ad bard or ap bard(even worse than ad bard) or jungle bard builds gonna get shred to pieces against some1 who is atleast decent.
Im saying that iI prob could get s+ as AD brand or AP graves in silver,but that doesnt mean its good and doesnt mean it will work further when u climb higher.
So sticking to ur ad bard will win u games but overall wont make u climb higher than where u are now,because once u hit a certain border u will be seen as trol,it will not work anymore(any Cait,jhin,sivir with atleast vision of how adc played and aware of ur range for auto wont leave u any chanses to win lane),and u will get demoted back to place where ur ad bard works..and well..whole circle will start again.
Its better to aim for most efficient playstyle/build for ur champ and learn how to use it if ur aiming to climb,because even if full supp bard will work less in silver(arguable,since a huge part of dmg comes from meeps,not scales on abilities,which means for early/mid game if played properly u wont see difference),but suppBuild will mean more in gold,even more in plat and will become musthave in dia and higher.
But if ignore all that shit above said,and to answer ur original question,no sticking to jungle bard or AD thresh wont make u climb faster,and it definetly wont make u better,same with expanding ur champion pool too much.