There's a blog wherein Pavel gives a three-month plan for adding variety to S&S. That would be good for you. I think the number of days per week varies from two to five, and the volume varies - each four-week block is broken up into one week each of 300, 400, 600, and 700 swings. The volume per day varies between 60 or 80 on the low end and about 200 on the upper end.

So, if you're stuck with 3 days a week, or even 2, you can still make this work.

Here's a link to that blog

From Simple to Sinister: Waving Volume on S&S | StrongFirst
Here's what I think is a good thought about implementing a plan like this - my wife and I both use this approach for a variety of lifting things, just not swings:

Map out your months, map out the weeks for each month, map out the individual sessions for each week, and have that printed (or otherwise easily accessible). Then make it your mission to complete each month somehow, but vary the days within a week and the weeks within a month as your schedule allows.

E.g., every Sunday night, look at your upcoming work schedule and ask yourself where it works best for you to have days off, where you might fit in the highest volume days, and where you might be OK with some of the middle-volume days. Once you have a target for the week, as long as you meet the weekly goal, you should be OK, but there's nothing wrong with shuffling the order of the sessions within the week. And the same goes for shuffling the weeks within the month if, e.g., you know you need an easy week before a big work project or a trip (or perhaps you want the easy week after the trip instead).

Create your own target - if 2000 swings per 4-week period doesn't work for you, pick another number. If you need to fit in all your swings over 3 weeks instead of 4, just make the math work. If you know you're going to be on vacation, make it a lower-volume month.

And although the article doesn't touch on this (I don't think), play with varying volume over different months, too, e.g., instead of 2000 every 4 weeks, do more some months, less others, and make the average still be the kind of volume you want to achieve overall.

S&S is brutally simple; if you're willing to do the math, and adjust your training to your schedule while still keeping track of the math, you'll still reap the rewards of consistent training with sufficient volume.

-S-