alfea is fairys houme for 5 years. why did winx wus there just 3>?

i thk because they got there enchantix

When they got their Enchantix they had to leave but when they earn their believix they go back as teachers for the rest of the years

it's because the got the new levels of powers fast like they were the only ones who had they charmix in alfea in season 2 they were the only ones who had they enchantix too so that why i think that