Is it better to maximize sleep, or align to ~1.5 hr cycles
Neither
Sleep cycles do not have a set length.

sleep for 7 hours every night and you won't interrupt a sleep cycle. 6 hours may be fine for a person but it is unlikely.  

You feel tired when you interrupt a sleep cycle becasue many of the sleep inducing hormones are still present in your system.
http://apsychoserver.psych.arizona.edu/jjbareprints/psyc501a/readings/Carskadon%20Dement%202011.pdf

If you are sleeping different lengths every night (or say sleeping longer on the weekend) that will also make you feel tired. Normally your body adjusts the length of your sleep cycle to how long it predicts you will sleep for, if that is constantly changing however it cannot do this and you often wake up in the middle of a cycle making you feel tired. Sleep the same length of time for ~14 days and you will see your sleep cycle stabilize.   

http://journals.sagepub.com/doi/abs/10.1177/1534650103259743

https://www.researchgate.net/profile/Martin_Moore-ede/publication/15765130_Human_Sleep_Its_Duration_and_Organization_Depend_on_its_Circadian_Phase/links/557881b308aeb6d8c01f1715.pdf

http://healthysleep.med.harvard.edu/healthy/science/what/sleep-patterns-rem-nrem