With my country in lockdown for the foreseeable future, I have a lot more time in the day that I'm not spending on commuting and out of home hobbies...

I'm fortunate that I'm self-employed, and can continue working from home during all of this - but at much lower time investment.

Would it be fruitless to try to juggle a quasi-retreat schedule (6-8 hours/day) alongside some intellectual work?

Has anyone experimented with something like this before?

Hey John,
Here am I : smiling stone's home retreat log
I don't know if you can find anything helpful for you in that, but... it's doable, and not a waste of time hopefully!
John W just started one as well here

Goodluck if you decide to do it... and otherwise as well.

with metta
smiling stone

I'll be doing one this coming Friday to Monday to use some PTO.  I will be likely doing a semi-set schedule targeting 7 or more hours of formal practice per day.  Prepping by getting all chores/essential errands done earlier in week.  I benefit from structure so creating a schedule in advance is helpful for me.  

Beyond that I have held many all-day`retreats on the weekend for me & friends at my house.  People were able to come & go between sessions.  I have a set schedule in those cases with 5 minute breaks between sitting & walking that makes it realistic so we can actually keep to it.  Then lunch in the middle & with noble silence.  

The turning point for me with home retreats was Dhammarato saying "you could practice all day every weekend if you really wanted to." I realized it was my own limiting beliefs preventing me from making it happen.  Then I just did it.

Just a follow up in case anyone reads this and is inspired.
 
DO IT. So long as you're not placing worldly responsibilities aside.

This has been a massive boost to my practice and I have never felt happier. 

I believe I may have achieved SE as I posted in my other thread (where before I think I was deluded). Even If a month or few down the line I was deluding myself, there is no denying that this is the most 'successful' - if you can really call it that - my meditation has ever been.