This didn't used to be a problem in the days when tour timings and tickets had to be sent out to passengers by snail-mail, so had to be confirmed well in advance rather than sent via e-mail a day or two before.
Therefore it strikes me that this is the usual situation, train planning departments which have been under-resourced, under-funded and (where multiple organisations are involved), fragmented. Hard working people up against tight deadlines and charters end up at the bottom of the pile.
I'd love this to be improved under GBR, but imagine it probably won't be as the government tries to cut everything to the bone.
You still used to get tickets sent out sometimes with estimated timings, and you'd give a number to call when booking for if there were any last minute alterations.
Trouble I've found, and I used to be involved with planning them, is you'd often get totally useless bids from the operators, trying to do moves that are physically impossible, either for the train or in the case of steam support work like tankers (wanting hoses dragged across running lines for watering is not unknown!), sometimes through booked possessions, and with timings that sometimes are impossible even with no other traffic on the line, let alone trying to weave in and out of existing services.
The number that could have been, and sometimes should have been, rejected outright was quite high, but out of principle we didn't, but bids were meant to essentially work already when submitted to Network Rail, but too often we got guesstimates, which obviously take much longer to deal with, then when what you send back looks nothing like the original impossible bid, you start getting to and fro 'negations'; "can we do this instead; can we change the start time; the finish time's too late, but we still want 3 hours at the destination, no still no good; but what if we went this way instead; oh we've had lots of bookings, we need to add more coaches; we need to plan for a different loco....." all resulting in alteration after alteration, after alteration, so it gets later and later sending out the final timings.