I don't think is is necessary to use my grow lights for sweet potato slips. I just put the potato in a mason jar on the table that is an east facing patio door. When the slips are about 8" long, I pull them off and put into a water filled mason jar to root. The process takes about 10 weeks and they are ready to go into the ground after hardening them off, like any other plant. They don't get 24/7 light in nature so I am not sure what your objective is in doing so. Let us know.

The question is whether or not 24/7 light would be helpful or not. If the roots can grow a little faster, or the slips can grow a little faster, or if there really isn't an effect, or if there is a negative effect. If they might do better in full sun, instead of under the shade of a tree, why wouldn't even more sun be better? Or light, in this case. Especially since I'm using incandescents, and the slips are supposed to like extra red light.

Incandescents are very inefficient. Use t-5,t-8 shoplights

It's on a windowsill, so it gets real sunlight, but I'm still wondering about whether or not 24/7 light is beneficial.

I think this is a case of overthinking. If normal lighting does the job, there's no benefit to extra lighting. The only reason to even try to force slips to grow faster than they usually do would be if you started them too late.

As a general rule, starting plants max out on light at about 12-16 hours.

Start them early enough to grow without 24/7. They will not be growing in 24/7 when they are in the real world.

I took cuttings from the garden for the past two falls and rooted then in water for a few days, then stuck them in the greenhouse for the winter. They grew LONG and leggy, lost their leaves, etc. But when spring was near, it was a simple matter of cutting the stems into about 8 inch lengths, root in water for about a week, and they were ready for the garden. Tons of them..... I had a fine crop of sweetpotatoes, growing as ground cover under the tomatoes. Think I will move them this year to the orchard through the wood chips.... I better put some in the raised beds as well, as I want a good crop again. They are wonderful!!!