I think that this type of activities is very effective. The continuous writing allow to remember the basic words and basic ortography rules with easier. Before I writing weekly, I don't could remember and I don't had present in my mind basic words.
I know that I improvement my vocabulary, but also I have become faster to write and this make me happy.
About the topics, I consider that is more easier writte about popular topics, for example: family, university, pets etc. the ideas and things for comment in the blog coming faster to my mind, in contrast, topic as jobs or sport are difficult to address because not all of we are related of direct form, this make more difficult writting diferent items of the same topic.
In the future I think that will be useful to combine writing with listeng, for example, in the laboratory session, watch a brief report of a news channel (With free link, for see the time necessary) and we give our opinion. I think that will be positive because allow train the hearing, when I hear once is difficult for me recognize all pronunciations, but when i can repeat the audio, I can recognize more words.