I agree with that strategy and was going to try it
myself, but couldn't get free from work long enough to make
any multi-days.
I figured when I could ride a "comfortable" 35, I
was ready to move up to 50s. I was correct, however have had issues
with OTHER things that I had not prepared for. In particular, I needed to
up my mare's nutrition because her diet for 25s was not sufficient to keep her
energized for 50s. Hopefully the changes I've made to her diet will prove
worthwhile. There are MANY other things that I'm learning now that I've
moved up to 50s--mainly in making sure I'M ready and am prepared to better take
care of my horse. I think that aspect of moving up is harder than making
the horse ready...
Others have far more experience than I, but my
strategy is to do back-to-back or multi-day LDs to prepare a horse for
50s. Then to do multi-day 50s to prepare for 100s.