I definitely don't think masters lifters necessarily need to drop down to twice weekly. I'd say that's fairly extreme, and would really only do that because of scheduling issues rather than training itself.
There's nothing that says you have to train with high volume and/or intensity every day you train. In fact, lifters of all ages modulate volume and intensity day to day to allow recovery. The same model just needs to be adjusted for the master according to individual need.
Because mobility is often a huge issue for masters, I think more frequent training is a good idea to help preserve mobility and to actually help recovery. So while you may only have 2 heavyish days/week rather than the 3-4 of a younger lifter, but you can still have 2-3 additional days on which you work more technical exercises, or stick to lighter work.
I do think it's a good idea to start conservatively and increase frequency incrementally to find the right balance for yourself.