Fundamentals
Every-N-day schedules
Last reviewed · Written by the PepCycle team
An every-N-day schedule repeats on an interval, not on a weekday. Unless N is 7, it drifts against the calendar — every-3-days lands on a different weekday each week. Most tracking apps model schedules as weekday checkboxes, which cannot represent this at all, so users are forced into an approximation that slowly becomes wrong.
Why every-3-days is hard
A weekly schedule is easy because seven divides the week. Any other interval does not, so the schedule walks around the calendar:
| Interval | Pattern | Same weekday? |
|---|---|---|
| Every 1 day | Daily | Yes, trivially |
| Every 2 days | Mon, Wed, Fri, Sun, Tue… | No — alternates weekly |
| Every 3 days | Mon, Thu, Sun, Wed, Sat… | No — drifts continuously |
| Every 7 days | Same weekday | Yes |
| Every 10 days | Drifts by 3 days weekly | No |
This is not an edge case. Every-other-day and every-third-day patterns are common in peptide protocols, and "5 on, 2 off" is a distinct shape again. A tracker built around seven weekday checkboxes can express none of them.
The anchoring question
When an entry happens late, the next one is due... when exactly? There are two defensible answers, and an app should let you choose rather than silently picking one.
- Anchored to the schedule — the plan is fixed, and a late entry does not move the next due date. The schedule stays aligned to its original anchor.
- Anchored to the last entry — the interval is what matters, so the next due date counts N days from what actually happened.
Other schedule shapes
- On/off cycling — a period of entries followed by a defined break, repeating. Requires a cycle length and a start date, not a weekday.
- Titration — a sequence of changes over time, where the schedule itself changes at defined points. See GLP-1 titration tracking.
- Multiple compounds on different intervals — a stack where each compound has its own interval, so the calendar has overlapping rhythms rather than one.
- Tapering — a planned wind-down, which is a titration in reverse and equally deserves to be recorded as a plan.
Each of these is straightforward to model correctly and impossible to model with weekday checkboxes. The workaround people are pushed toward — setting a daily reminder and ignoring most of them — trains you to dismiss the reminder, which defeats the point.
How PepCycle models it
- Every-N-day intervals as a first-class schedule type, with N as any integer.
- On/off cycles with explicit lengths and a start date.
- Per-compound schedules, so a stack's components can run on different rhythms without fighting each other.
- Explicit anchoring, so you choose whether a late entry shifts what comes next.
- A calendar that shows the whole shape rather than a flat list of today's reminders.
See how PepCycle compares to trackers built on weekly assumptions.
Frequently asked questions
Why can't my tracker do every 3 days?
Because it models schedules as weekday checkboxes, which can only express patterns that repeat weekly. An every-3-day interval drifts across weekdays continuously, so there is no set of checkboxes that represents it.
If I take a dose late, when is the next one due?
That depends on anchoring. Anchored to the schedule, the next due date is unchanged. Anchored to the last entry, it counts the interval from what actually happened. Both are defensible; an app should let you choose rather than deciding silently.
How do I track an on/off cycle?
As a cycle length with a start date — for example a defined number of weeks on followed by a defined break, repeating — rather than as a list of individual dates. Recording it as a shape means the calendar can project it forward.
Can different compounds run on different schedules?
They should be able to. A stack where one compound is every other day and another is weekly is entirely ordinary, and forcing both onto one rhythm makes the record wrong for at least one of them.
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