I have struggled to get the bare minimum consistency into my practice. For a long time, I only did magic when I needed it and dealt with gods or spirits only when they poked me. That's pretty much the metaphysical equivalent of only running when you're late and considering that your exercise - it means you're not prepared for the work when you have to do it, and it means that in times of peace and plenty you're putting the important things off.
I've experimented with seasonal celebrations, monthly cycles, weekly devotions, and using seven-day candles to mark my activities. The problem with all of these, for me, was that missing one set me back a lot. You miss Beltane and you're off til Midsummer - or, if you're trying to do your ADF writeups, you're starting over. Obviously this works for a lot of pagans, and weekly practice works for millions of mainstream religious.
It doesn't work for me. For me it's pretty much daily practice or nothing. Screwing up daily practice leaves me only 24 hours to feel like a failure. It means I don't feel I have to "go big or go home." The more inconsistent my practice is, the more I feel I have to go all out when I do get around to it. Then I get worked up about it, my perfectionism kicks in, and it all falls apart again. Or religious scrupulosity eats my brain, and I'm irrationally afraid Odin's going to smite me or something.
Right now, my daily practice is pretty much limited to tending Mara's altar, lighting a candle or two, and meditating for fifteen minutes or so. I don't even manage the meditation every day, but it's something I always benefit from having in my practice when I can make myself stop and do it. I'm slowly adding my housekeeping to that, since I'm trying to do it with intent. It's not fancy, it's not Work-with-a-capital-letter. But it works for me. Better baby steps that work than inconsistent leaps and falls.