Missing grammar: parallel structure

I've been researching learner language using the Cambridge Learner Corpus for 20 years now and there are certain issues that crop up again and again among learners at all levels. One that I pick up on regularly is illustrated in the examples below (made up examples rather than real corpus data, but they illustrate the point):

At the weekend, he goes to the park and play football. (subject-verb agreement)

I like playing football and run. (verb + -ing form)

I'd love to visit Paris and seeing the Eiffel Tower. (verb + to do)

We went to the park and play football. (past simple verb form)

We can swim in the sea and playing volleyball on the beach. (modal + verb form)

I've tided the kitchen and did the washing up. (present perfect/past participle form)

I was sitting on the train, chatted to my friend on the phone. (past continuous/-ing form)

Basically students attempt to use a second verb form (usually) after a conjunction without repeating the subject, but they forget to match the verb form to the start of the sentence. In each of the examples above, the correct form would become clear(er) if we inserted the 'missing' subject (+verb/auxiliary/modal):

At the weekend, he goes to the park and [he] plays football.

I like playing football and [I like] running.

I'd love to visit Paris and [I'd love to] see the Eiffel Tower.

We went to the park and [we] played football.

We can swim in the sea and [we can] play volleyball on the beach.

I've tided the kitchen and [I've] done the washing up.

I was sitting on the train [and I was] chatting to my friend on the phone.

It's something I've noted in countless corpus reports, but I've never been quite sure what to call it. Until last week when I came across it for the first time in an ELT coursebook referred to as parallel structure. It was in a B2 book in a section about academic writing style and covered a wider range of structures than those above (not just verb phrases, but nouns, adjectives and full clauses too), but it still made me cheer out loud at my desk. It's long puzzled me why these incredibly common structures aren't explicitly addressed in most ELT materials when they cause so many issues for students.

I rarely get the chance to choose the grammar points I cover in the materials I work on, because they're mostly supplementary materials and the syllabus is already fixed by the time I get started. So I've never had the opportunity to cover this explicitly myself. I have tried to include examples in practice exercises, but they usually end up getting cut by editors who want all the items to fit on a single line and don't like the longer examples these structures often involve (grrr!).

So I'm making a case for this to be included explicitly in more ELT materials. It's relevant at every level and with almost every kind of verb structure we teach. It doesn't have to be a separate grammar point and it doesn't even have to have the label parallel structure. I think it's a great thing to bring up when you're revising a particular verb form as a slight variation on the usual practice activities, just to raise students' awareness. You could have a simple intro as above showing/eliciting the 'missed out' words and the correct second verb forms. Then straight into some practice examples (as gap-fills or freer practice). It works perfectly for any kind of list: 

• daily routines (She leaves the house at 8 and catches the bus at 8.15)
• a dramatic narrative (He opened the box and looked inside)
• background to a narrative (People were sitting in the café, eating and drinking)
• things people like doing (I like watching TV and chatting to my friends online)
• things people would like to do in the future (I'd like to go to university and study drama)
• things ticked off on a list (We've booked a room for the party and set up a Facebook page)
• things on a to-do list (I still need to confirm the hotel booking and renew my travel insurance)

I'm happy to be proved wrong with a flurry of comments about ELT materials that practise exactly this already ...