to be honest, i never did intro with my boy who is a pb as i went straight in at PN, but i never did any "proper" canter work with him for it, as he was resonably fit anyhoos as he was ridden everyday and jumping 3 times a week etc. he never had a problem getting the time for PN, and has never felt tired - he kept travelling at the same pace.
i ride H at least 5 times a week, with prob 2 schooling sessions and maybe a jump session- though he finds it so easy i tend to maybe pop over a few jumps every few weeks. Usually do 1 1/2 hrs hack with lots of trot/canter work and about 45mins if schooling. am just concerned as i know since hes Idxtb he needs quite a bit of work to keep fit enough for a xc round, just wonder how long he should be able to canter for in order to be ok at an intro xc. obv its about 4mins at a comp but theres all the other bits to consider as well.
When I brought mine back into work after a Christmas break my fitness regime consisted of (after the interminable weeks of walking etc!!):
Interval training - 3x3 minute canters twice a week (as part of schooling/hacking)
One really thorough jumping session a week
2 x schooling sessions
1 longish hack round fields (all paces)
Bear in mind my boy is a nightmare to hack out on the roads so this doesn't feature heavily in our schedule.
He is now going PN happily within the time and with plenty left in the tank at the end.
Sounds to me yours is doing enough work at home to be fit enough for Intro. I would maybe give a good canter about 5/6 minutes 4 or 5 days before an event but too be honest you would be fine withot.
usually it works out like this:
Monday - schooling session, usually flatwork
Tuesday - used to go to a rally, now do a schooling session
Wednesday - 1 hour hack and then canter work in field
Thursday - jumping session
Friday- dressage possibly jump a few jumps depending on what we are doing on the sat
Sat - usually competing, if not then jumping session or a hack
sun - day off.
that is a normal week for me, i dont call that fittening work
if i was trying to get him much fitter i would do loads more hillwork and trotting, go to the gallops at least once a week and i would ride him twice a day and go for early morning hacks before school and then when i got home from school i would school him!
we are about to move up to novice so this plan will be put into action