Is there a difference between trying to get (for example) 1300 mg calcium a day or just trying to spread 9.1g over a week? Are there certain nutrients that must be consumed in a certain quantity every day? Logically it seems more realistic to use larger time intervals but vitamin solubility is said to affect retention?
Depends on the nutrient, how much of it we can absorb, over how long and how our body manages excess. In most cases you shouldn’t be taking a few days’ load in one sitting, for example. Usually no problem with minor fluctuations between days, but it could be relevant if it’s insulin levels, for example. You shouldn’t consume more than 500mg calcium over 4-5 hours, and no more than 2500 per day, internet says:
https://muschealth.org/medical-services/geriatrics-and-aging/healthy-aging/calcium
Generally speaking if you’re getting it from food it shouldn’t be a problem at all to average it out over a few days. With my clients I work off of food diaries and they average the nutrients so if you do a 3 day diary I’ll be given stats for your daily average and your average nutrient density per megajoule of energy. Obviously with some things like water soluble vitamins we will generally pee out excess, but if you didn’t get enough the previous day, chances are you’ll be able to utilise more the next day, so there won’t be excess to pee out. Somethings have absorption limitations, so trying to get all your nutrients once a week probably wouldn’t work, but humans wouldn’t have survived this long if our bodies couldn’t function relatively well on sporadic access to nutrients. We’ve adapted to a certain level of that.