If it ain't broke don't fix it ... Raw Linseed Oil ( RLO ) was the traditional finish used on Lee Enfield rifles and many Military rifles during both World Wars and after - it's not totally waterproof and is still permeable but you need to finish the stock with a wax polish to seal it. You can mix 50/50 Tung oil and BLO if you like also.
I have treated many military rifle stocks using ( BLO ) Boiled Linseed Oil which has Japan Driers added to it to speed up the drying process. It offers an excellent finish if done correctly. As to applying Linseed Oil every three months, well that is complete overkill! A rifle stock needs reapplication of Linseed Oil every 2 years at minimum and even that is probably too much. Every rifle stock is a case by case situation ... you can over oil a rifle stock also and every three months is ridiculous.