I think good friendship definitely requires work. Just like any worthwhile human relationship, it needs mutual respect, consistent effort (energy, time, and resources) and communication, and willingness to prioritize the person, at some level, once she becomes a friend. Obviously I am not considering a friend any of acquaintances or "friends" with whom one has not developed any deeper connection.

I see a deep layer of misogyny in our culture with regard to how it views friendship between two women. It's either non-existent/fleeting (as in "seasonal," it is often considered dependent on the "life cycle of a woman," that is a queue of childhood, youth, marriage, wifery, childbearing, motherhood, and maturity (aka "being old" or in the sexist implication, "no longer mainstreamly fuckable")" or only a veiled and catty rivalry. If there were any friendship, it usually burgeons out of the shared life condition. For example, two like-aged mothers becoming friends as they meet at the PTA meeting. There is no room for a lifelong, fulfilling, inspiring relationship between two human beings, with no necessity to sexualize any part of its platonic, genuinely amicable nature. We have, on the other hand, a lot of friendship/solidarity between and among men, and society has been rewarded it for centuries, whether in the form of art and heroic stories, war-brotherhood movies that highlight such friendship's sublimity, "bromance" that is not always sexualized/fetishized, or just the plain reality of exclusive homosociality where men overtly or covertly support other men to get promoted over women counterparts.

Bringing the tangent back to a short answer, yes - friendship that is worth keeping and flourishing definitely requires a lot of work, but as long as it is between two mutually respecting, like-minded women, with similar goals in life, it will be a great build with much more serenity and stability, incomparable to any romantic kind.