Learning and doing other activities on Erev Shabbos:
One is to slightly diminish the amount of his learning on Erev Shabbos. It goes without saying that one is to diminish from doing other activities.
Yeshiva on Erev Shabbos: [Due to the above requirement to diminish in ones learning on Erev Shabbos in order to have time to prepare for Shabbos] the custom in some places is to not have a set Yeshiva learning Seder on Erev Shabbos.
Private learning: One who is accustomed to learn a certain Torah subject daily is not to nullify this session on Erev Shabbos if it is a clear subject that will not lead one into debates and analysis. [If he does not learn this subject on a daily basis then based on the above custom, he is to nullify it.] A subject which is customarily learned on Erev Shabbos, such as the commentary of Rashi on the weekly portion, is allowed to be learned as usual [even if it is not studied on a daily basis].
Shnayim Mikra: Is to be learned on Erev Shabbos. See Chapter 285
Having a Shiur on Erev Shabbos: A Shiur which is given on a regular basis, is to likewise be given on Erev Shabbos if it involves a non-complicated subject which has a limit and will thus not be carried into debates and analysis. This allowance applies even if this Shiur is not given on a daily basis. [One however is not, based on the above custom, to give a Shiur on a subject which involves debate and analysis.]
Learning with a Chavrusa: Seemingly this follows the same laws as does a Shiur [explained next] and is to be learned if the subject has a limit.
Going shopping prior to learning the permitted subjects: If one will be unable to purchase his Shabbos needs after his learning Seder then he is not to set his learning [of the permitted subjects] for the morning, which is the time that the items are available for purchase.
If ones Shabbos needs are already cared for: [In all the above cases] if one already prepared all his Shabbos needs on Thursday, or he has someone else who is able to do so for him [on Friday] then there is no need for him to diminish in his learning or other activities.
If one’s Shabbos needs are being taken care of by others, or he has already prepared them on Thursday, then he may continue his learning sessions as usual, without limitation.
If however one needs to personally prepare for Shabbos then he is to diminish in his learning sessions and is only to learn in the following scenarios:
- It is a non-complicated subject which he learns daily and does not involve long analysis.
- It is a public learning session which does not involve long analysis, even if not learned daily.
- Is a subject which is meant to be learned on Erev Shabbos, like Rashi in Chumash.
The above applies only if one has time to still purchase his Shabbos needs at a store. If however the store will be closed by the time his learning session is complete, then he must first go to the store in the morning prior to learning.
Vetzaruch Iyun why Admur moved the original place of this Halacha from chapter 251, as written in the Rama, to this chapter 250.
 The reason for this is in order so one is available to prepare the Shabbos needs. [ibid]
 Whether in the Beis Midrash with Chavrusas, or a Shiur given by a Maggid Shiur. [Kuntrus Achron 1]
 As the learning which is done within the forum of a Yeshiva does not have a set time limit being that it is common to enter into long Torah debates and analysis. We thus suspect that these debates will carry on for a long time and they will not be left with any time to prepare their Shabbos needs. [ibid]
 From the wording of Admur it implies that it is regularly given, however it does not have to be given daily. However in truth one can say that this includes even a case that the Shiur is set only for Erev Shabbos and is not learned any other day of the week. Vetzaruch Iyun.
 Kuntrus Achron 1
 So is implied from Kuntrus Achron 1. However Tzaruch Iyun how many people have to be learning together for it to be considered “Public” as is a Shiur. As well Tzaruch Iyun if the learning must be done in a Beis Midrash, as is discussing the case of Admur, in order for it to be defined as similar to a Shiur.
 The novelty here is seemingly that in a case that one’s set time for learning will not give him enough time to reach the store, then he is not to make his learning Seder earlier in the morning and then go shopping but is rather to first go shopping and then have his set Seder. If however ones set learning time is in the morning with enough time left to make the purchases, then there is no need to delay the learning session. Vetzaruch Iyun.
 Admur wrote this allowance in 250/2 and then went on to write the above mentioned limitations in 250/3. There thus requires analysis as to whether the allowance is referring to also all the cases mentioned in 250/3. Logically speaking the allowance does apply, as there is no longer need to worry of not having time to prepare for Shabbos. So seems to learn also the Ketzos Hashulchan 70/5 which does not mention any of these laws and simply states if ones preparations are taken care of, no diminishing of his learning is needed. So is also evident from Magen Avraham 251/6 which mentions this allowance only after mentioning all the learning limitations mentioned above, and then concludes “If one prepared on Thursday he may learn as usual”. However Tzaruch Iyun why Admur did not then write this allowance at the end of 250/3, after mentioning all the limitations, as is commonly done in the wording of “Beme Devarim Amurim”, and rather chose to mention it in 250/2 in the Halacha discussing diminishing learning and activities.
The Kaf Hachayim 251/22 rules that one who has someone else available to prepare his Shabbos needs for him, then he may continue learning as usual.