How many projects should you do at a time?

Future front fence location to the left of the screen across front of driveway to new corral. 

Just how many projects should you work on simultaneously?  I have a couple, maybe a few.  I am currently attempting to get the new corral up and working.  I started in on the drain line for the gutters that come off of the end of the barn.  The gutters off the end of the barn need to be done, The main irrigation pump channel needs to be finished digging but that requires me to rent a backhoe for a day.  I need to finish working on the irrigation pump fittings.  I need to pull the small irrigation pump and get it fixed.  I need to finish digging the hole in the yard so I can install two more no freeze outside spigots in the yard.  I decided to start drilling holes today for the new front fence across the driveway.  I have some help coming for a day next week so I am going to have them work on the front fence and the gutters on the barn.  Hopefully, the corral will be finished by then.  I still need to install the scratching post and fly powder triangle stand for the cows.  Of course it is time to start spraying the star thistle again this year.  I purchased a few hundred dollars in herbicide yesterday, so I need to use it up. 

I have a couple more projects in my head but not actually started so I didn't think they would count.  I wanted to run the new fence gate right up to the concrete walkway but the buried telephone line runs directly in the corner next to the driveway.  I know this because I cut it in half once already when installing the lights (which no longer work because they need to be rewired.).  The corral hopefully will only take us two more days.  I only have Phil for two more days, so it needs to be done in two days!  I think it is possible.  One of the items coming up is cleaning up the old house.  It is a mess from all my projects this year.  I need to spend one day just cleaning up and putting stuff away. 

New corral taking shape. I did not use a level if you had not noticed.  It is a corral.