AJ, remember long is relative. For some, 5 minutes may be unduly long.
To me, the value of RD isn't in following an RD ascent profile versus my Shearwater. The value is in understanding the decompression obligations the parameters of the dive will give me before ever running them. Being able to quickly determine how much deco obligation I would be looking at for a given dive before splashing in the water, or how altering a variable (depth or time) mid-dive impacts the rest of the schedule, has a lot of value.
For example, I don't need to run a full ascent schedule via dive planning tools on a 150' dive for 40 minutes to know it's going to be about an 80 minute run-time and I can quickly determine if we have enough gases and/or the conditions are good for the dive plan. RD lets me quickly determine if a dive plan is acceptable (or not) before running a complete schedule in a planning tool. It doesn't take me 5 minutes of running a profile in dive planning software to determine 190' for 40 is a 2 hour run-time, or 240' for 40 is a 160 minute run-time, etc.
BTW, although I deco out on my computer, I have a dive plan in place before splashing in the water. I use RD as a tool before any other planning just to see if the plan is acceptable, or not.
