My 2 cents worth!
I learned to fly in a C150 with an instructor that was insistent on nose high fully stalled landings.
I did my tail wheel endorsement in a J4 Auster when I had about 100 hrs. A complete pig of an aeroplane but once I got the hang of keeping it straight using its almost useless rudder (at low airspeeds anyway) and awkward heel brakes, I had very little troubles with it. Maybe 3 hrs dual. Only ever did 3-pointers and was told "you can't wheel an Auster" by someone who know what he was talking about (WWII Wirraway instructor) - so I never tried. Doing a TW endorsement without a good workover on wheel landings is a serious deficiency in my opinion.
Next taildragger was a J1 Auster. Much more responsive to rudder input than the J4.
Then I towed gliders in a Pawnee 235 - but that shouldn't count cause you could fly than thing like a NW aircraft and would have to try hard to come to grief. Easiest TW I have ever flown.
A mate had a C180, and I was fortunate enough to be able to fly that pretty well as much as I liked until I was comfortable and competant. Did a couple of hrs of circuits ICUS and then maybe 10 hrs solo in a very short space of time. His brother then bought a C185 and I got to drive that a lot, both ICUS and solo. I was never totally confident in the 180/185 until I had mastered tail-low wheelers. Fantastic experience that I didn't have to pay for!
I have also flown Tiger Moth and Harvard.
After I did an Instructors Rating, I used to do TW endorsements in a PA18 Super Cub. What a fun little aeroplane! You could do wheelers and 3-pointers till your heart's content in that sucker, and turn messed up wheelers into 3-pointers and vis versa! While I had some interesting excursions with pilot's coming to grips with their first TW aeroplane, I never felt I might "loose it".
I have never flown Citabria/Decathalon but I figure they would be much the same.
I think an initial Tail Wheel endorsement should be a minimum of 3-5 hrs dual depending on the candidate, and should cover the principles of why they are so keen to depart from a straightline roll on TO and Landing, how to position the control surfaces when taxying, TO and landing in winds from all points of the compass, and a thorough workout on 3-pointers and wheelers both into wind and in various x-winds.
Somewhere in another thread I have related the story of someone who learnt to fly in a C150, did their navs in a C172 and then, with about 50 hrs in their log book, insisted on doing an intial TW endorsement in a C185 - it ended in tears!
Dr 