"prisma linnainmaa tarjoukset" is a common search among shoppers in Finland looking to plan their regular shopping around current pricing and promotions. For Prisma, specials and promotions are generally published on a weekly cycle, so checking the most recent catalogue is more reliable than relying on results that may reference an older promotional period.
Comparing multiple retailers rather than committing to one by default tends to produce better value for a typical shopping list, since promotional depth and timing genuinely differ retailer to retailer even within the same country.
The full catalogue directory for Finland brings together current offers from multiple retailers in one place.