Presumably there is some reason you want a cleaner house, e.g. it will be easier to find stuff. If you spend 90 minutes cleaning, that will get you half as much gain in terms of making it easier to find stuff. So it's still worth doing in its own right. (Similarly, every marginal minute of exercise buys you 3-7 marginal minutes of life (within reason). Etc. This doesn't work for everything but it works for some things.)
Make a plan that you can do in 90 minutes, where the outcome will be better than the starting position.
Next time, make another 90-minute plan.
Maybe this will be less effective in total, e.g. you might need three or four 90-minute sessions to accomplish what you could do in a single 180-minute session. But if the 180-minute session is unavailable, this is the best option you have.
For example: Instead of vacuuming the whole house, do one room at a time. Instead of putting all things to their places, on day 1 collect all things and put them into a temporary basket, and on day 2 take a few random things from the basket and put them where they belong.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.