at wt 3 it's very difficult to remove anything with wt 1 in my exp. if something is in in wt 3 it means that at least 2 ppl have added it out of 3 which means that even if 4th player doesnt add he wont remove it. if only 1/3 have added it wont be in so scythe will have to reap.
1/3 segs out
so if at wt 4 someone has completed something and it's missing something it's bc he/she didnt catch it to reap it in.
It's impossible for a player with normal wt 1 to remove anything in a wt 3 cube. only a scythe (or admin) can remvove and only if 2/3 have added it, if 3/3 have added it then more scythes are required (or 1 admin).
Unless conf lvls change ofc.
4th player can add but only if at least 1/3 has added, so it's not in in wt 3 but wt 4 makes it 2/4 instead of 1/3 and adds it but unless it's a merger it may not be a bad thing as it may have been something the 1st completing scythe missed.
I'd say it's imho better that 2 scythes cooperate to sc at the same time same things so they can lock rather than wait for whole branch/cell to be wt 4. But that's me