Manitas is right about using proper 48 bar tunes. In fact some of the best jigs and polkas I know are 48 bar tunes - there's no excuse for doing the AABBAB thing.

The version of Four Seasons with the 1st part in G and the other 2/3 in D is a magnificent example - you certainly know when you've arrived back at the beginning of the tune!

Here's some cracking 48 jigs:
Cream Pot
Bang Upp (John Clare ms)
4 Seasons
The Feathers
The Valiant (Simon Ritchie)
Basquet of Oysters (as played by Old Swan Band)
When Daylight Shines
Morgan Rattler
(and that's before we scrape old warhorses like Sweets of May, Dingle Regatta, Blarney Pilgrim and Merrily Kiss The Quaker off the bottom of the barrel...)

Anahata