Recording calcs for the day is great advice, I used to just scribble my math on some scrap paper or on the plan set, usually it would end up lost or just be some gibberish numbers on the plan. I made a Google sheet that auto calcs my slope % for each run. I just enter my starting and stopping elevations and run lenthgs and it spits out slope, everything is auto saved, I just make a new sheet for each job/task. Takes some of the guesswork out of it and gives a good record of what was installed. I always Calc my own slopes, I've caught many errors on plans, or had to adjust slopes due to how the engineer calced them. Example being some engineers draw pipe runs center of structure to center of structure, but really your actual pipe run is probably 4' less than that depending on what you're doing. Low slope stuff this isn't a big deal, but if you're running 15% (can be common here) you can end up .6' off on elevation. Good practice to always Calc your own slopes and double check