When we think of such a question a few training principles come to mind. We have your basic model of linear programming where each week the volume increases or the load does to drive the stimulus that leads to the desired adaptation. This approach relies heavily on specificity of movement and progressive overload to keep getting stronger. The other programming approach is conjugate that supplements a max effort day into the schema of the program with the intention of straining against something heavy each week to create the stimulus that drives the adaptation. This approach uses a variety of bars and exercises to allow for a novel stimulus each time and to try and mitigate the repeated bout effect. By doing this you will have some weeks where the absolute load is high and some where it is lower but no matter what you are straining.
Both programming styles have there pro's and con's. When trying to decipher what is the best approach for a given athlete one must factor a few things. The sport of choice, the time frame in which to accomplish the goal, athlete buy-in, training age and history, and what's worked for them in the past. Some coaches love to switch up exercises to decrease absolute load as they feel it is easier on the athletes joints and prevents wear and tear injuries. This is very common in strength sports even though there is no real evidence to support that claim. Others like being able to see week to week progress through progressive overload principles and creates less of a guessing game as to what is and is not working in your program.
What does the Research Show?
In a study conducted by Doorslaer de ten Ryen et al. 2021 they looked at hypoxic training versus normoxic training to see which training state would induce more muscle thickness and a higher fractional protein synthetic rate. They found that there was no difference between groups. They did find that the hypoxic group improved strength gains in the leg extension. Keep in mind that both groups performed the exact same exercise program of 6 sets of 10 reps in the single leg extension at 80% of 1rm 3x a week. The only difference was the conditions of the test, unfortunately there are some holes in the research design and the paper that doesn't give us the insight we would need to really flesh out this idea but it does make you think. Why would the hypoxic group improve strength but no other markers?
The best guess here on why the hypoxic group improved would be that the perceived effort was harder in the hypoxic group versus the normoxic group due to the ability to breath normally was hindered. Because it felt harder there was more of an adaptive response to the training even though the load and training was identical. This is just speculation of course but it should make a coach think what is more important, the perceived effort or the absolute load to improve strength. Some times within research they make you ask better questions and as a coach you should constantly be doing so in order to keep improving.
Effort or Load?
When looking through the research we see time and time again that perceived effort plays a huge role on the athletes ability to endure amongst other variables and very little research has been done on this type of an idea in resistance training. But if perceived effort plays a huge role than the conjugate training philosophy may be onto something and finding ways to make exercises harder without using absolute load may be a good way to do a training block or two.
References:
van Doorslaer de Ten Ryen S, Warnier G, Gnimassou O, Belhaj MR, Benoit N, Naslain D, Brook MS, Smith K, Wilkinson DJ, Nielens H, Atherton PJ, Francaux M, Deldicque L. Higher strength gain after hypoxic vs normoxic resistance training despite no changes in muscle thickness and fractional protein synthetic rate. FASEB J. 2021 Aug;35(8):e21773. doi: 10.1096/fj.202100654RR. PMID: 34324735.