No character needs stamina and in some respects TA/A is slightly better than most since it has longish recharges on the debuffs meaning less reactive use of your primary than most Defenders and no toggles so most of your end usage comes from archery.
That being said my TA/A has Stamina because I'm lazy 
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I remember when I was leveling up a TA/A, I thought I could go stamina free but one of the Arch blasts is brutal for endurance and once I selected it, I noticed blue bar draining a lot faster. I think it was the fire arrow (whatever it's called). I don't have access to City of Data at work any more to see the specifics. But I did want to mention that your perception may change soon.
Global = Hedgefund (or some derivation thereof)
It used to be a case of TA living without stamina rather easy, partially down to longer cast times. The longer the cast time the more end recovery you have between the activation of each power. However since then people have asked for a reduction in cast times. Some people found they spent each fight debuffing and just as they were about to use a secondary, gorramit the group is dead, onto next! Real end loss comes from the secondary. I could probably dig up where people have said that teaming with TA, groups get flattened in no time.
Nowadays good end recovery is alot more necessary but where you gonna get it? A lot of TAs powers do not self stack so knowledge on not over using a end heavy powers needlessly helps along with slotting your powers for end redux. Later you might get EMP arrow which has an adverse effect on your end recovery, as a panic button you might never know exactly when your going to use it and how low your endurance bar maybe at the time. So conserve energy is very nice. I hasten it.
I have two builds one is with stamina and one is without stamina, the more offendery one is infact the one with stamina and the defendery one is without stamina. You can from vigilance, save on endurance, but I find thats not quite enough so a mix of end slotting, hastened conserve and not over using any debuffs which wouldn't stack anyway keeps my endurance just good enough. By the time I am through my chains I hit conserve, carry on, be up to full end and in need of conserve just as it recharges. That build proved a tight build down to the last slot. At 50 putting the last slot in did it actually really work out.
I will suggest cohtitan redtomax site for coverage on what powers do and any guide here, the more recent the better.
He will honor his words; he will definitely carry out his actions. What he promises he will fulfill. He does not care about his bodily self, putting his life and death aside to come forward for another's troubled besiegement. He does not boast about his ability, or shamelessly extol his own virtues. - Sima Qian.
Hello all, I have a lvl 10 trick arrow/arrow defender and I am trying to get used to the play stlye, having never had a debuffer before (which is what a guild-mate of mine told me I am with that toon... lol) and so far, end use hasn't been an issue for me. Will it be later on? Should I start the path to stamina at 21? Any tips you can give me on this power set and debuffing in general? TIA!