Handle progression for single time per week muscle groups

[raven-black-dream]

Describe the bug
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To Reproduce
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Expected behavior
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If I muscle group is worked 1 time per week it should perform the progression functions more gracefully.

Currently the progression algorithm assumes that a kusclemgroup is worked more than once per week. Which means that the current workout data should not be used to determine progression. However in the case of single time per week muscle groups the baseline for progression should be the current workout.

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Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
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