In response to your earlier post, here are some cursory observations on training differences over the decades (you will certainly be able to find swim coaches who will disagree with some of these summaries, so consider these one old coach's observations only)
60s - Swim training mimicked the moderate/long rest interval training used by runners. You can find the Jim Ryun training log online as trained by his HS swim coach Timmons. The track intervals there are similar to the swim workout intervals used in that decade. No goggles so daily swim mileage ranged from 3,000 meters to (in double workouts) 10,000 meters. As Jefe in CO noted in his post, weight training is minimal.
70s - Short rest interval training in the pool is pretty standard in all successful programs (to the extreme of doing repeat 400 meter swims with only 10 seconds rest between!) Goggles are universal and swim mileage balloons to major programs doing 15,000 - 20,000 meters PER DAY! Australians popularize the running LSD to the pool with great success in longer distance swim racing. Even weight training is popular as short rest interval circuit training, eg. swimmers rotate from weight station to weight station doing 45 seconds of work and 15 seconds to switch to the next station.
80s - still high swim mileage but not as much as in the 70s. Heavy weight work becomes popular with nautilus type machines being available. Exercise scientists promote low yardage training as beneficial and more quality work is incorporated in many programs.
Efforts to "train smarter" include widespread lactate testing in workouts to find optimal training intensities.
90s - Some core strength training with med balls gains popularity. Higher quality sprint work programs developed. Recent swim podcast includes 90ish Auburn head swim coach, now Olympic coach testifying to his success as a sprint swim coach being due to his incorporation of Auburn Track coach sprint training protocols back then.
(editorializing on my part now....1 - do running coaches ever incorporate anything from swim coach colleagues? 2 - 90s saw Michael Jordan effect, i.e. very few Big Males show up in the sport of swimming in this decade)
00s - increased focus on quality work for both distance and sprint swim training (most programs still believe in double workouts, but not necessarily every day) . Weight training significantly diversified and free weight work embraced more universally. Big men return to the sport (editorializing). Huge increase (almost 100%) in number of age group swimmers joining the sport and so "cream rises". Top programs daily mileage around 5,000-7,000 for single workout days and 10,000-12,000 for double workout days, but specific sprinter training probably around 60-70% of that mileage.
10s - Age Group professional swimmer Michael Andrew popularizes a "new" training called USRPT (ultra short race pace training), which basically incorporates the short rest interval work begun in the 70s with low daily mileage and high level repeat speed. (a sample track workout using USRPT would be 20-30 x 200s with 20-30 sec rest between repeats holding your 800 PR pace on the 200s.)