I think I would have had a hard time mentally accepting a version of
Time as a Fleetwood Mac album that only had Billy Burnette as a vocal holdover from their previous (and worst ever, in my humble opinion) album... yes, Mick and John would have been on it, but come on...
In fact there is evidence that Christine was to be involved in 1993 with what was to become
Time - go to about 8;10 on this video (filmed just before the Clinton inauguration). There was also an interview with her at around the time of
The Dance when she said that her participation in the recording of
Time was a contractual obligation..
https://www.youtube.com/watch?v=4Lc7hE9TIr0
"It's quite well publicised that I had planned not to tour again with Fleetwood Mac, so my excuse is that a girl can always change her mind.so you know, i don't know I would like to do a few concerts here and there and certainly pursue a solo career as well..hopefully Fleetwood Mac are going in the studio in April or thereabouts to make another album"
I think this was around the time that Billy had left which might explain the absence of his guitars from her songs and the use of Michael Thompson instead...Dave and Bekka joined in 1994, initially without the involvement of Billy, so the non-Christine tracks may have been recorded in 1994/5 with a few overdubs here and there on the Christine tracks.
Just my theory..but I am inclined to believe that Christine's tracks were recorded first, not that her songs were then recorded later to rescue the album. Not that they did, in terms of sales...
I think by that point (January 1993) Stevie may have pulled the plug on recording with them as well as touring... but it's all a bit murky...