Can speed practice alone help long distance endurance?

I disagree strongly with the notion that "25/50/100/200m based training" is not "endurance work," though I guess maybe that's your point? Tons of studies out there show that interval-training, with distances short relative to the target race, will improve performance in that race. How "endurancey" it is depends on the number of reps and the rest interval. Sorry, I should have specified that I meant training (by all means) to improve over these distances (50/100/200). I am somehow familiar with the notion of broken distances (aerobic intervals) as composing 90% of most swimmers' regiment. And to tell you the truth, it's a notion that the original poster explicitly mentioned and somehow got ignored until your post. (to the op) If it was your original question, then yes most 100% sure that breaking down your distances in smaller chunks is a generally accepted way of developing endurance. Say you want to do 2000 of moderate endurance pace work (purely aimed at developing endurance), you may split this thing into chunks of 50 m and still be on target. You just got to make the rest period smaller. But what I actually meant is that it is highly important for triathletes (to name these) coming from a running background (to name this) that they should first learn to swim fast, then extend the durations (much later into their season). A lot of these folks have a 1500 around 27, a 100m around 1:30. They'd better get this thing down to at least 1:15 before thinking of solely focusing on endurance development (like they sometimes do). That turns some of them into "diesel" swimmers. For me, swimming fast somehow is a certificate of stroke efficiency. Any 1500 "specialist" that doesn't have a 100 near 1:10 would probably improve faster over 1500 more by improving on the 100 first. It's primarily what I meant.

I disagree strongly with the notion that "25/50/100/200m based training" is not "endurance work," though I guess maybe that's your point? Tons of studies out there show that interval-training, with distances short relative to the target race, will improve performance in that race. How "endurancey" it is depends on the number of reps and the rest interval. Sorry, I should have specified that I meant training (by all means) to improve over these distances (50/100/200). I am somehow familiar with the notion of broken distances (aerobic intervals) as composing 90% of most swimmers' regiment. And to tell you the truth, it's a notion that the original poster explicitly mentioned and somehow got ignored until your post. (to the op) If it was your original question, then yes most 100% sure that breaking down your distances in smaller chunks is a generally accepted way of developing endurance. Say you want to do 2000 of moderate endurance pace work (purely aimed at developing endurance), you may split this thing into chunks of 50 m and still be on target. You just got to make the rest period smaller. But what I actually meant is that it is highly important for triathletes (to name these) coming from a running background (to name this) that they should first learn to swim fast, then extend the durations (much later into their season). A lot of these folks have a 1500 around 27, a 100m around 1:30. They'd better get this thing down to at least 1:15 before thinking of solely focusing on endurance development (like they sometimes do). That turns some of them into "diesel" swimmers. For me, swimming fast somehow is a certificate of stroke efficiency. Any 1500 "specialist" that doesn't have a 100 near 1:10 would probably improve faster over 1500 more by improving on the 100 first. It's primarily what I meant.