I’m confused. Are you hitting your gravities? If so, there is no issue. Keep on doing what you’re doing.

If not, I’ll answer your question about batch sparging. Any system will take a few runs to learn the intricacies of. I’ve learned about how much volume I’ll get for my first runnings from a given amount of grains and water. I also have figured out my general mash efficiency (which will change slightly for each recipe even if all else is exactly the same). So it will take some brews and some guessing at first, but take detailed notes and you’ll learn what you can reasonably expect.

From there, you can take measurements along the way to gauge. I take a gravity same for each “batch” and also note the volume. This means I can calculate my total gravity points and know my pre-boil volume and can estimate my post-boil gravity based on my usual boil-off rate. Or you can take a gravity reading once everything is in the kettle and boiling (to ensure homogeneity due to the mixing boiling provides)—but by then you’ve added everything and there’s no going back—only adjusting by boiling longer or adding extract.