If you've looked at the recipes I've produced, you'll have seen how many different types of sugar were employed. They weren't just thrown in randomly. The varying sugars each had their own properties and purpose.
"It is well to remember, however, that invert and cane sugars yield
luscious beers which do not maintain much condition in cask for any
length of time. Dextrinous sugars blended with invert somewhat remedy
this transient condition. Glucose yields dry and possibly thin beers,
but those which possess a peculiar flavour of their own are more
suitable for quick consumption. Then again, high-dried malts, mashed
fairly low, yield beers which in their earlier stages possess
palate-fulness and lusciousness. Pale malts, mashed high, yield beers
which during early storage lack condition and palate-fulness, but which
improve in condition and in fulness the longer they are kept. Any sugars
employed which have dextrin present are suitable for beers which are to
be stored more than a fortnight, and the percentage of such sugars used
should vary according to the length of storage of the beers. Then
again, the quality of the sugar employed for priming in cask materially
affects palate-fulness and permanent condition, and in the production of
stouts we have to consider the question of the mashing temperatures
employed; these should be suitable for the quality of the caramelised
matter used in the mash-tun; otherwise the diastase will not correctly
do its work, as there will not be sufficient of it to carry out the necessary conversion of starch into saccharine matter."
"A Treatise of Practical Brewing and Malting" by Frank Thatcher, The Country Brewers' Gazette, 1905, pages 294 - 295.
It's obvious why invert and cane sugar (sucrose) would create beers whose condition didn't last long. Being highly fermentable, they would be quickly consumed by the yeast. Such sugars were clearly best suited to running beers, which needed to come into condition quickly.
On the other, sugars high in dextrin, which is much less readily fermentable, would provide food for the yeast to slowly nibble through during a long secondary fermentation.