I think you might be stressing yourself out. As long as you work with a sense of urgency and try your hardest you'll be okay, and they'll recognize that, as they already have in your review. Most LOD's understand that there are things that will take time away from your zone (helping guests, answering calls, backup, etc) and realize that there are a few isles that may not get done. It's extremely, extremely unlikely you would get anything more than a verbal coaching for not getting to an isle or two. There will always be that one anal LOD who might say something, but beyond that I don't think you have anything to worry about.
Something that may help you out is setting a time limit for yourself. We'll say 3-5 minutes per isle depending on the section and the isle you're in. Spend that amount of time and no longer, then you have to move on. Don't get caught up super-zoning a section or isle, because the LODs will notice an unfinished zone before an amazing section or isle, unfortunately. Understand that guests are going to shop and your zone will get messed up, but you have to get through your zone first, and then go back through and do touch-ups as needed. I'm a lot like you when it comes to zoning, and I've found that setting those time limits for myself has been a big help. It also helps to start at an end of the section that sees less guest traffic, and work towards the end that gets shopped more. For example, if I'm zoning in G one night (consumables, mini, seasonal, and automotive for us), I start at automotive, and end my zone in consumables, because that's the area that gets shopped right up until close, and automotive is generally a ghost town. Ideally by zoning that way you're spending less time going over things twice. I hope this helps!
What marketandsoftlines said. Don't spend too much time in one aisle - instead of superzoning it, just face it and move on. Then, if there are any aisles (not isles, an isle is an island) that are in particularly rough shape, you can go back and restore order to them later. Keep in mind: you'll also need to leave yourself time to get your re-shop worked.
Just do a speed zone if they want it done no questions asked. I've found a lot of leaders don't care if you're accurate or not, they just want everything faced.
I won't lie, I was annoyed when cashiers would overzone, because it wasted time when we could be moving on to additional tasks. Heck when I worked flow at walmart, EVERYONE cut corners on their zone, but if you didn't get done, they hated it.
I started wearing a watch at work (vs. looking at my phone) to help me keep track of time so I make sure I'm not spending too long in a particular area. Since then, I'm able to budget my time a lot better and I'm able to complete my zone sooner.