Word strength not decreasing (Spanish Tree)

[Skye07]

I noticed that 4 of the lessons I haven't done in months do not decrease in word strength. They are grammatical ones so I know I'm not practicing them in other lessons.

They are (word strength between brackets): V. Sub/Imp (3), V. Modal (2), V. Cond. (3) and V. Sub. P. (1)

I don't mind they don't decrease rapidly but after a month or 2 of not practicing one might think they'd go back to 1 bar or 2 bars but not stay at 3.

[ekampel]

my word strengths are not decreasing at all.

[DKenney404]

None of my strengths seem to be decreasing either. I do practice often, but after 2-3 days of no duolingo everything remains 5/5.