When I practice to build up my strengths, per category, it does not upgrade. Ex: I practiced my "Places" skills and as of today (July 15, 2017) it should be upgraded to 5/5, not as shown 4/5. I need to see that this practice is done so that can attempt to make progress. FYI- This is the third time this has happened this week. Thank you.
The skill strength is an average of the strength of the words in that skill. As not all words come up in a single practice, or even in many practices, it is possible that there is still a word or a number of words with low strength which is bringing the average down.
In general, redoing the individual lessons of the skill will mean a greater number (which should be all, but sometimes perhaps isn't all) of the words will be strengthened. Getting a word wrong many times will lower its strength and accordingly lower the average.