limits to stretching - don't over do it

If I cannot follow the standard stretching series (hopefully, only temporarily) of 1x front split/middle split/thorasic bridge a week but I have two or three slots of 10-20 mins a day and want to fill them with stretching, which muscles / joints are safe to do every now and then? I remember all the exercises from the stretching series very well and I can play with them in all possible ways so my concern is about volume and frequency in order to not overdo the stretching, risking no-results or even injury. Any tips on that, please? I know that would be all individual but there might be some general tips? Thanks a lot in advance! 

Hey Andrey simply follow the sequence...and do it when is possible...one series every 3 days? ok....no problems.

Thanks, Alessandro!!!