I've posted a lot on the past with my Vasa experience as AOS swimmer that's low on talent but over the years have gotten myself into the top 15% of swimmers in my tri races. (Which means I get my doors blown off by any competitive 10 year old girl swimmer.)

I haven't been on my Vasa more than 6 times in the past 2 years. It's because my kid got old enough to leave at home alone (finally!) and the erg is so boring in comparison. Water is fun!

In the past year, I significantly increased my CONSISTENT all pool (No vasa) swim volume, to the point that I'm averaging about 15k/wk. (I do about 18k, 17k, pullback week of 13k in a cycle.) This is about 100% more pool volume than I did previously, and about 50% more volume compared to my prior pool+vasa which was usually in the 10k/wk estimate range if combining both.

I have gotten faster in OWS races, but no huge breakthrough for sure. Just more consistent top 12-15% finishes in the swim, whereas before with pool+erg it would be in the 15-20% range. I honestly think that if I just did my prior pool+vasa combo at the equivalent volume I'm doing now, I'm nearly certain that I'd be about the same speed on race day. For sure, all pool hasn't been the huge magic breakthrough that I'd hoped it would be compared to vasa+pool.

I also respect SnappingT's swim coaching expertise, but I just can't square his claims the the erg is useless. I'll agree that some dryland training techniques that will address parts of the stroke better than the erg will, but having done almost all of these cord and other motions, there's no way I'd prefer them over the erg for replacing large volumes of swimming. (As a supplement to pool swimming, they work great, yes!) If the erg was useless, there's no way I should have been doing as well as I was on like 4-8k/wk of swimming + erg.

For me the erg worked well for supplementing and even replacing a good amount of pool time as a non-FOP swimmer. Even now, I seriously question whether some of my sessions would be better replaced by just doing 90 minutes on the erg compared to driving 30 minutes to swim 60, or doing 60 minute erg+30min bike or run, since my results were so similar with pool+erg compared to all pool now. Again, the only reason I don't, is that swimming is just fun, and the erg is so boring.

And for sure, if was seriously time-constrained like I was with my young kid, where getting to the pool during swim times that weren't a circle swim disaster, I'd highly recommend using the erg to amp up whatever limited pool time one can get. I do think Sam Gyde's results are quite plausible, and what I'd expect. I also think that people are probably overestimating his swim improvement if he just goes all-pool compared to the erg - I think he'd get slightly faster, but only slightly. I seriously doubt he'd suddenly be like 10 minutes faster on an IM swim, and even 5 would even be a really good result.