Fidelity supports auto roll, so I set up a ladder by buying the same amount every few weeks with the same maturity. I wanted a three month efund of $13k, so I bought $2k 13-week t-bills every two weeks, and $1k on the thirteenth week. I started that earlier this year and the auto roll went through without a hitch.
I have the other half of my efund (the other 3 months) in Ibonds, but I’ll probably end up moving that to t-bills now that I bond rates are less interesting and I prefer having everything in one place anyway. So I’ll do that by buying 26 week t-bills and converting the 13-week t-bills as well.
It’s a little bit of a pain to set up, but once it’s going, it’s completely hands off. If you’re lazy, you can just buy a t-bill fund and get pretty much the same benefit, but I like owning the bills themselves for some reason. Since it’s a brokerage, you can do whatever you like.