Juice - if every five days works out for you, your schedule and your levels, then sure. Many go twice per week to keep their levels more stable. Some do once a week because it's less hassle and they don't feel any ups and downs with the high/low levels. Some go every 10 days and they don't feel any worse off for it either - it all depends on the person. I go every 3.5 days because I can put it on my calendar and make it easy to remember - every Thurs morning and Sunday night. If you pin every 5 days (or 10 or whaterver) you actually have to count and remember to pin yourself

Like Bob said, you have to log things...
When I was traveling for work more, I'd inject once per week on the weekend so I wouldn't have the hassle of taking needles and meds through security at the airport.
So, that was a long response to 'opinion of every 5 days' hehe.