If you notice the BTC price drops on the weekends. This may be why they don't use bots, and only trade on weekdays; excluding holidays. They use the weekend to drop the price of BTC. So they can pump it up throughout the following week.
...On average, the price drops about $20 USD during the weekend; only to begin rising around Tuesday-ish.
I like the idea of a noticeable pattern, and I'm sure that everyone trading coin would love to take advantage of cyclical events, but looking at the last 3 months of bitstamp prices, I don't see what you see as far as a pattern goes. Please correct me if I am wrong.
NB: I modified, in Kolour, a chart I copied from bitcoincharts.com, to highlight the weekends vs weekdays.
[snipping photo so the Post Wall of Doom doesn't manifest!]
I was just going by what I notice using CoinWarz, defaults to Coinbase's price. Which I believe is Bitstamp's price. Because Coinbase is more like a PayPal with BTC service than an actual trading exchange.
But with your chart. You can see that at the start of the Weekend there's typically a sell off (red candle) and a rally starting around Tuesday into Wednesday (green candle). This is, of course, not true if there was a selloff during the Friday-ish day on this planet, meaning it can start as early as Thursday for 'negative' GMT countries (I'm 6hrs behind, myself).
It's not much of a change, but it is a noticeably predictable
cycle. I emphasis cycle because the change is so small, that I usually see it go back up above the point I had initially looked at in the morning on CoinWarz.
Meaning: I get up, check. That becomes the 'high'. Refresh a few hours later and the new 'high' is ~15 - 25 USD below the previous. By the time I go to bed the 'high' is now above the high I remembered seeing when I first checked. However, this change doesn't seem to happen much during the Weekday, unless something panics the crowd (damn you China; stahp eet!); again with the same casual glances.
NOTE: I do not chart watch. But I do casually refresh every few hours to check the prices on alt coins and just curiosity of what's going on in BTC Land (ie: Large drop, "oh shit, what happened; let's check the news tab of Google for 'Bitcoin'").
So far I've done...6 cashouts; 4 of those were not reinvestment payments. However, all were requested on Saturday (on purpose). And I believe all by one resulted in my BTC deposit being worth more than when it had been requested. Believe the one happened on the coat-tail of the New York BitLicense thing being announced.
FYI: I'm in no way suggesting BT has the ability to do this (and not be in the middle of a collapse; a la MtGox style). But they may have seen the pattern that people tend to sell off their earnings on the weekends. So it's hard to justify running any trades when the overall trend of BTC Pricing is downwards....instead you'd want to be buying and waiting till about mid-week to sell off.
This might also explain why the rates are so consistent. What's the difference between being paid 1% per day and 7% per week? ...just the psychological mind game that you think you're being paid more.
So, you do the massive trading (per week) during the cyclical cycle of 'up' and 'down' per week and minor trading. Then, per day, use the massive trading (per week) to smooth over the per day trading results.
** It's an interesting theory. That could work. Really, ~1% per day isn't that hard to achieve if you're watching what you do and do get greedy. It's even easier if you have a buffer created at the start of each week, when you bought up a bunch of cheap BTC from the weekend. It also would sort of explain the reluctance to be audited as that would likely show the weekly in/out of money (in this case money being BTC).
--Remember, Google doesn't want to disclose how much power their Search Engine farms use because it would give insight into how their 'secret sauce' code indexes searches.**